QuickLinks -- Click here to rapidly navigate through this document

As filed with the Securities and Exchange Commission on August 9, 2004

Registration Statement No. 333-            



SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM S-8
REGISTRATION STATEMENT
UNDER
THE SECURITIES ACT OF 1933

NeuroMetrix, Inc.
(Exact name of Registrant as Specified in Its Charter)

Delaware
(State of Incorporation
  04-3308180
(I.R.S. Employer Identification No.)

62 Fourth Ave.
Waltham, Massachusetts 02451
(781) 890-9989
(Address of Registrant's principal executive offices)

NeuroMetrix, Inc. Amended and Restated 1998 Equity Incentive Plan
NeuroMetrix, Inc. 2004 Stock Option and Incentive Plan
NeuroMetrix, Inc. 2004 Employee Stock Purchase Plan
(Full Title of the Plan)

Shai N. Gozani, M.D., Ph.D.
President and Chief Executive Officer
NeuroMetrix, Inc.
62 Fourth Ave.
Waltham, Massachusetts 02451
(781) 890-9989
(Name, address, including zip code, and telephone number, including area code, of agent for service)

With copy to:
H. David Henken, P.C.
Goodwin Procter LLP
Exchange Place
Boston, Massachusetts 02109
(617) 570-1000

CALCULATION OF REGISTRATION FEE


Title of
Securities Being Registered

  Amounts to
be Registered(1)

  Proposed Maximum
Offering Price
Per Share

  Proposed Maximum
Aggregate
Offering Price

  Amount of
Registration Fee


Common Stock, par value $.0001 per share   1,018,235 shares (2)   $4.18 (3)   $4,256,222.30 (3)   $539.26

Common Stock, par value $.0001 per share   825,000 shares (4)   $7.76 (5)   $6,402,000.00 (5)   $811.13

Common Stock, par value $.0001 per share   375,000 shares (6)   $7.76 (5)   $2,910,000.00 (5)   $368.70

Plan Interests (7)   N/A   N/A   N/A   N/A

Total Fee               $1,719.09

(1)
This Registration Statement also relates to such indeterminate number of additional shares of Common Stock, par value $.0001 per share, of NeuroMetrix, Inc. ("Common Stock") as may be required pursuant to the NeuroMetrix, Inc. Amended and Restated 1998 Equity Incentive Plan, as amended (the "1998 Plan"), NeuroMetrix, Inc. 2004 Stock Option and Incentive Plan (the "2004 Plan") and NeuroMetrix, Inc. 2004 Employee Stock Purchase Plan (the "ESPP") in the event of a stock dividend, reverse stock split, split-up, recapitalization, forfeiture of stock under such plans or other similar event.

(2)
Represents 1,018,235 shares of Common Stock that may be issued upon the exercise of options granted under the 1998 Plan.

(3)
This estimate is made pursuant to Rule 457(h) under the Securities Act of 1933, as amended (the "Securities Act"), solely for the purposes of determining the amount of the registration fee. The price per share and aggregate offering price are based upon the weighted average exercise price of the options granted under the 1998 Plan.

(4)
Represents 825,000 shares of Common Stock initially available for issuance under the 2004 Plan.

(5)
This estimate is made pursuant to Rule 457(h) under the Securities Act of 1933, as amended (the "Securities Act"), solely for the purposes of determining the amount of the registration fee. The price per share and aggregate offering price are based upon the average of the high and low sale prices of the Common Stock reported on the Nasdaq National Market on August 6, 2004.

(6)
Represents 375,000 shares of Common Stock initially available for issuance under the ESPP.

(7)
In addition, pursuant to Rule 416(c) under the Securities Act, this Registration Statement also covers an indeterminate amount of interests to be offered or sold pursuant to the ESPP. In accordance with Rule 457(h)(2), no separate fee calculation is made for plan interests.





PART I

INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

Item 1. Plan Information*

Item 2. Registrant Information and Employee Plan Annual Information*

*
Information required by Part I to be contained in the Section 10(a) prospectus is omitted from this Registration Statement in accordance with Rule 428 under the Securities Act of 1933 (the "Securities Act") and the Introductory Note to Part I of Form S-8.


PART II

INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3. Incorporation of Certain Documents by Reference

        Incorporated by reference in this Registration Statement are the documents listed below, which have previously been filed by NeuroMetrix, Inc. (the "Company") with the Securities and Exchange Commission (the "Commission"):

    (a)
    the Company's Prospectus dated July 22, 2004 as filed with the Commission on July 22, 2004 pursuant to Rule 424(b) under the Securities Act relating to the Registration Statement on Form S-1, as amended (File No. 333-115440); and

    (b)
    the description of the Company's Common Stock contained in the Registration Statement on Form 8-A (No. 000-50856) dated July 19, 2004 as filed with the Commission on July 19, 2004 pursuant to Section 12(g) of the Exchange Act and any amendments or reports filed for the purpose of updating such description.

        In addition, all documents subsequently filed by the Company with the Commission pursuant to Section 13(a), 13(c), 14 or 15(d) of the Exchange Act, prior to the filing of a post-effective amendment which indicates that all securities offered have been sold or which deregisters all securities then remaining unsold, shall be deemed to be incorporated by reference in this Registration Statement and to be part hereof from the date of filing of such documents.

        Any statement contained in a document incorporated or deemed to be incorporated by reference herein shall be deemed to be modified or superseded for purposes of this Registration Statement to the extent that a statement contained herein or in any other subsequently filed document which also is incorporated or deemed to be incorporated by reference herein modifies or supersedes such statement. Any such statement so modified or superseded shall not be deemed, except as so modified or superseded, to constitute a part of this Registration Statement.


Item 4. Description of Securities

        Not Applicable.


Item 5. Interests of Named Experts and Counsel

        Goodwin Procter LLP, Boston, Massachusetts, will pass upon the validity of the shares of Common Stock of the Company offered by this Registration Statement.


Item 6. Indemnification of Directors and Officers

        Section 145 of the General Corporation Law of the State of Delaware provides that a corporation has the power to indemnify a director, officer, employee, or agent of the corporation and certain other persons serving at the request of the corporation in related capacities against expenses (including attorneys' fees), judgments, fines and amounts paid in settlements actually and reasonably incurred by the person in connection with an action, suit or proceeding to which he is or is threatened to be made a party by reason of such position, if such person acted in good faith and in a manner he reasonably



believed to be in or not opposed to the best interests of the corporation, and, in any criminal action or proceeding, had no reasonable cause to believe his conduct was unlawful, except that, in the case of actions brought by or in the right of the corporation, no indemnification shall be made with respect to any claim, issue or matter as to which such person shall have been adjudged to be liable to the corporation unless and only to the extent that the Court of Chancery or other adjudicating court determines that, despite the adjudication of liability but in view of all of the circumstances of the case, such person is fairly and reasonably entitled to indemnity for such expenses which the Court of Chancery or such other court shall deem proper.

        As permitted by the Delaware General Corporation Law, our Third Amended and Restated Certificate of Incorporation, or certificate of incorporation, includes a provision that eliminates the personal liability of our directors for monetary damages for breach of fiduciary duty as a director, except for liability (1) for any breach of the director's duty of loyalty to us or our stockholders, (2) for acts or omissions not in good faith or that involve intentional misconduct or a knowing violation of law, (3) under section 174 of the Delaware General Corporation Law (regarding unlawful dividends and stock purchases) or (4) for any transaction from which the director derived an improper personal benefit.

        As permitted by the Delaware General Corporation Law, our Second Amended and Restated by-laws, or by-laws, provide that (1) we are required to indemnify our directors and officers to the fullest extent permitted by the Delaware General Corporation Law, subject to certain very limited exceptions, (2) we may indemnify other employees as set forth in the Delaware General Corporation Law, (3) we are required to advance expenses, as incurred, to our directors and executive officers in connection with a legal proceeding to the fullest extent permitted by the Delaware General Corporation Law, subject to certain very limited exceptions and (4) the rights conferred in our by-laws are not exclusive.

        We have entered into indemnification agreements with each of our directors to give such directors additional contractual assurances regarding the scope of the indemnification set forth in our certificate of incorporation and to provide additional procedural protections. We also intend to enter into indemnification agreements with any new directors in the future. At present, there is no pending litigation or proceeding involving any of our directors, officers or employees with respect to which we may have indemnification obligations.

        The indemnification provisions in our certificate of incorporation, by-laws and the indemnification agreements entered into between us and each of our directors and executive officers may be sufficiently broad to permit indemnification of our directors and executive officers for liabilities arising under the Securities Act of 1933.

        We have obtained liability insurance for our officers and directors.


Item 7. Exemption from Registration Claimed

        Not Applicable.

2




Item 8. Exhibits

        The exhibits listed below represent a complete list of exhibits filed or incorporated by reference as part of this Registration Statement.

    *4.1   Third Amended and Restated Certificate of Incorporation of the Company

 

 

*4.2

 

Second Amended and Restated By-laws of the Company

 

 

*5.1

 

Legal opinion from Goodwin Procter LLP

 

 

*23.1

 

Consent of PricewaterhouseCoopers LLP, as independent auditors

 

 

*23.2

 

Consent of Goodwin Procter LLP (contained in the opinion filed as Exhibit 5.1 to this Registration Statement)

 

 

*24.1

 

Power of attorney (included in the signatory page to this Registration Statement)

 

 

  99.1

 

NeuroMetrix, Inc. Amended and Restated 1998 Equity Incentive Plan (incorporated herein by reference to Exhibit 10.3 to the Company's Registration Statement on Form S-1 (File No. 333-115440), as amended, filed on May 13, 2004)

 

 

  99.2

 

NeuroMetrix, Inc. 2004 Stock Option and Incentive Plan (incorporated herein by reference to Exhibit 10.5 to the Company's Registration Statement on Form S-1 (File No. 333-115440), as amended, filed on May 13, 2004)

 

 

  99.3

 

NeuroMetrix, Inc. 2004 Employee Stock Purchase Plan (incorporated herein by reference to Exhibit 10.6 to the Company's Registration Statement on Form S-1 (File No. 333-115440), as amended, filed on May 13, 2004)

*
Filed herewith


Item 9. Undertakings

        (a)   The undersigned Company hereby undertakes:

            (1)   To file, during any period in which offers or sales are being made, a post-effective amendment to the Registration Statement:

                (i)  To include any prospectus required by Section 10(a)(3) of the Securities Act;

               (ii)  To reflect in the prospectus any facts or events arising after the effective date of the Registration Statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the Registration Statement. Notwithstanding the foregoing, any increase or decrease in volume of securities offered (if the total dollar value of securities offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with the Commission pursuant to Rule 424(b) if, in the aggregate, the changes in volume and price represent no more than 20% change in the maximum aggregate offering price set forth in the "Calculation of Registration Fee" table in the effective Registration Statement; and

              (iii)  To include any material information with respect to the plan of distribution not previously disclosed in the Registration Statement or any material change to such information in the Registration Statement;

      PROVIDED, HOWEVER, that paragraphs (a) (1) (i) and (a) (1) (ii) of this Item 9 do not apply if the information required to be included in a post-effective amendment by those

3



      paragraphs is contained in periodic reports filed with or furnished to the Commission by the Company pursuant to Section 13 or 15(d) of the Exchange Act that are incorporated by reference in the Registration Statement.

            (2)   That, for the purpose of determining any liability under the Securities Act, each such post-effective amendment shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

            (3)   To remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold at the termination of the offering.

        (b)   The undersigned Company hereby undertakes that, for purposes of determining any liability under the Securities Act, each filing of the Company's annual report pursuant to Section 13(a) or 15(d) of the Exchange Act (and, where applicable, each filing of an employee benefit plan's annual report pursuant to Section 15(d) of the Exchange Act) that is incorporated by reference in the Registration Statement shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

        (c)   Insofar as indemnification for liabilities arising under the Securities Act may be permitted to directors, officers and controlling persons of the Company pursuant to the foregoing provisions, or otherwise, the Company has been advised that in the opinion of the Commission such indemnification is against public policy as expressed in the Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the Company of expenses incurred or paid by a director, officer or controlling person of the Company in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the Company will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Act and will be governed by the final adjudication of such issue.

4



SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, as amended, the Company certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Waltham, Commonwealth of Massachusetts, on this 9th day of August, 2004.

  NEUROMETRIX, INC.

 

/s/  
SHAI N. GOZANI M.D., PH.D.       
By: Shai N. Gozani, M.D., Ph.D.
Title: President and Chief Executive Officer

POWER OF ATTORNEY

        KNOW ALL PERSONS BY THESE PRESENTS that each individual whose signature appears below constitutes and appoints Shai N. Gozani, M.D., Ph.D. and Nicholas J. Alessi, and each of them, his true and lawful attorneys-in-fact and agents with full power of substitution, for him and in his name, place and stead, in any and all capacities, to sign any and all amendments, including post-effective amendments, to this Registration Statement, and to sign any registration statement for the same offering covered by this Registration Statement that is to be effective upon filing pursuant to Rule 462(b) promulgated under the Securities Act, and all post-effective amendments thereto, and to file the same, with all exhibits thereto and all documents in connection therewith, making such changes in this Registration Statement as such attorneys-in-fact and agents so acting deem appropriate, with the Securities and Exchange Commission, granting unto said attorneys-in-fact and agents, and each of them, full power and authority to do and perform each and every act and thing requisite and necessary to be done with respect to the offering of securities contemplated by this Registration Statement, as fully to all intents and purposes as he or she might or could do in person, hereby ratifying and confirming all that said attorneys-in-fact and agents or any of them, or his, her or their substitute or substitutes, may lawfully do or cause to be done or by virtue hereof.


        Pursuant to the requirements of the Securities Act of 1933, this registration statement has been signed by the following persons in the capacities and on the dates indicated.

Signature
  Title
  Date

 

 

 

 

 
/s/   SHAI N. GOZANI, M.D., PH.D.       
Shai N. Gozani, M.D., Ph.D.
  President and Chief Executive Officer and Director (Principal Executive Officer)   August 9, 2004

/s/  
NICHOLAS J. ALESSI       
Nicholas J. Alessi

 

Director of Finance and Treasurer (Principal Financial and Accounting Officer)

 

August 9, 2004

/s/  
CHARLES E. HARRIS       
Charles E. Harris

 

Director

 

August 9, 2004

/s/  
WILLIAM LAVERACK, JR.       
William Laverack, Jr.

 

Director

 

August 9, 2004

/s/  
DAVID E. GOODMAN, M.D.       
David E. Goodman, M.D.

 

Director

 

August 9, 2004

/s/  
W. MARK LORTZ       
W. Mark Lortz

 

Director

 

August 9, 2004

        Pursuant to the requirements of the Securities Act of 1933, the trustees (or other persons who will administer the plan) have duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in Waltham, Massachusetts, on August 9, 2004.

    NEUROMETRIX, INC. 2004 EMPLOYEE
STOCK PURCHASE PLAN

 

 

By:

/s/  
CHARLES E. HARRIS       
Charles E. Harris
Member of the Compensation Committee

 

 

By:

/s/  
WILLIAM LAVERACK, JR.       
William Laverack, Jr.
Member of the Compensation Committee


EXHIBIT INDEX

Exhibit
Number

  Description
*4.1   Third Amended and Restated Certificate of Incorporation of the Company

*4.2

 

Second Amended and Restated By-laws of the Company

*5.1

 

Legal opinion from Goodwin Procter LLP

*23.1

 

Consent of PricewaterhouseCoopers LLP, as independent auditors

*23.2

 

Consent of Goodwin Procter LLP (contained in the opinion filed as Exhibit 5.1 to this Registration Statement)

*24.1

 

Power of attorney (included in the signatory page to this Registration Statement)

99.1

 

NeuroMetrix, Inc. Amended and Restated 1998 Equity Incentive Plan (incorporated herein by reference to Exhibit 10.3 to the Company's Registration Statement on Form S-1 (File No. 333-115440), as amended, filed on May 13, 2004)

99.2

 

NeuroMetrix, Inc. 2004 Stock Option and Incentive Plan (incorporated herein by reference to Exhibit 10.5 to the Company's Registration Statement on Form S-1 (File No. 333-115440), as amended, filed on May 13, 2004)

99.3

 

NeuroMetrix, Inc. 2004 Employee Stock Purchase Plan (incorporated herein by reference to Exhibit 10.6 to the Company's Registration Statement on Form S-1 (File No. 333-115440), as amended, filed on May 13, 2004)

*
Filed herewith



QuickLinks

PART I INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS
PART II INFORMATION REQUIRED IN THE REGISTRATION STATEMENT
SIGNATURES
EXHIBIT INDEX

QuickLinks -- Click here to rapidly navigate through this document


Exhibit 4.1

THIRD AMENDED AND RESTATED
CERTIFICATE OF INCORPORATION
OF
NEUROMETRIX, INC.

        NeuroMetrix, Inc., a corporation organized and existing under the laws of the State of Delaware (the "Corporation"), hereby certifies as follows:

        1.     The name of the Corporation is NeuroMetrix, Inc. The date of the filing of its original Certificate of Incorporation with the Secretary of State of the State of Delaware was April 25, 2001 under the name "New NeuroMetrix, Inc." (the "Original Certificate").

        2.     A Certificate of Merger was filed with the Secretary of State of the State of Delaware on May 14, 2001 merging NeuroMetrix, Inc., a Massachusetts Corporation, with and into the Corporation under the name "NeuroMetrix, Inc." (the "Certificate of Merger").

        3.     The Original Certificate, as amended by the Certificate of Merger, was amended and restated by an Amended and Restated Certificate of Incorporation filed with the Secretary of State of the State of Delaware on December 19, 2002 (the "Amended and Restated Certificate").

        4.     The Amended and Restated Certificate was amended by a Certificates of Amendment filed with the Secretary of State of the State of Delaware on March 12, 2004 and June 21, 2004 (the "Certificates of Amendment").

        5.     The Amended and Restated Certificate, as amended by the Certificates of Amendment, was amended and restated by a Second Amended and Restated Certificate of Incorporation filed with the Secretary of State of the State of Delaware on July 15, 2004 (the "Second Amended and Restated Certificate").

        6.     This Third Amended and Restated Certificate of Incorporation (this "Certificate") amends, restates and integrates the provisions of the Second Amended and Restated Certificate, as amended by the Certificate of Amendment, and was duly adopted in accordance with the provisions of Sections 228, 242 and 245 of the Delaware General Corporation Law (the "DGCL").

        7.     The text of the Second Amended and Restated Certificate is hereby amended and restated in its entirety to provide as herein set forth in full.

ARTICLE I

        The name of the Corporation is NeuroMetrix, Inc.

ARTICLE II

        The address of the Corporation's registered office in the State of Delaware is 2711 Centerville Road Suite 400, Wilmington, New Castle County. The name of the Corporation's registered agent at such address is Corporation Service Company.

ARTICLE III

        The purpose of the Corporation is to engage in any lawful act or activity for which corporations may be organized under the DGCL.


ARTICLE IV

CAPITAL STOCK

        The total number of shares of capital stock which the Corporation shall have authority to issue is fifty-five million (55,000,000) shares, of which (i) fifty million (50,000,000) shares shall be a class designated as common stock, par value $0.0001 per share (the "Common Stock"), and (ii) five million (5,000,000) shares shall be a class designated as undesignated preferred stock, par value $0.001 per share (the "Undesignated Preferred Stock").

        The number of authorized shares of the class of Undesignated Preferred Stock may from time to time be increased or decreased (but not below the number of shares outstanding) by the affirmative vote of the holders of a majority of the outstanding shares of Common Stock entitled to vote, without a vote of the holders of the Undesignated Preferred Stock (except as otherwise provided in any certificate of designations of any series of Undesignated Preferred Stock).

        The powers, preferences and rights of, and the qualifications, limitations and restrictions upon, each class or series of stock shall be determined in accordance with, or as set forth below in, this Article IV.

A. COMMON STOCK

        Subject to all the rights, powers and preferences of the Undesignated Preferred Stock and except as provided by law or in this Article IV (or in any certificate of designations of any series of Undesignated Preferred Stock):

                                (a)    the holders of the Common Stock shall have the exclusive right to vote for the election of directors of the Corporation (the "Directors") and on all other matters requiring stockholder action, each outstanding share entitling the holder thereof to one vote on each matter properly submitted to the stockholders of the Corporation for their vote; provided, however, that, except as otherwise required by law, holders of Common Stock, as such, shall not be entitled to vote on any amendment to this Certificate (or on any amendment to a certificate of designations of any series of Undesignated Preferred Stock) that alters or changes the powers, preferences, rights or other terms of one or more outstanding series of Undesignated Preferred Stock if the holders of such affected series are entitled to vote, either separately or together with the holders of one or more other such series, on such amendment pursuant to this Certificate (or pursuant to a certificate of designations of any series of Undesignated Preferred Stock) or pursuant to the DGCL;

                                (b)    dividends may be declared and paid or set apart for payment upon the Common Stock out of any assets or funds of the Corporation legally available for the payment of dividends, but only when and as declared by the Board or any authorized committee thereof; and

                                (c)    upon the voluntary or involuntary liquidation, dissolution or winding up of the Corporation, the net assets of the Corporation shall be distributed pro rata to the holders of the Common Stock.

B. UNDESIGNATED PREFERRED STOCK

        The Board of Directors or any authorized committee thereof is expressly authorized, to the fullest extent permitted by law, to provide for the issuance of the shares of Undesignated Preferred Stock in one or more series of such stock, and by filing a certificate pursuant to applicable law of the State of Delaware, to establish or change from time to time the number of shares of each such series, and to fix the designations, powers, including voting powers, full or limited, or no voting powers, preferences and the relative, participating, optional or other special rights of the shares of each series and any qualifications, limitations and restrictions thereof.

2



ARTICLE V

STOCKHOLDER ACTION

        1.     Action without Meeting.     Except as otherwise provided herein, any action required or permitted to be taken by the stockholders of the Corporation at any annual or special meeting of stockholders of the Corporation must be effected at a duly called annual or special meeting of stockholders and may not be taken or effected by a written consent of stockholders in lieu thereof.

        2.     Special Meetings.     Except as otherwise required by statute and subject to the rights, if any, of the holders of any series of Undesignated Preferred Stock, special meetings of the stockholders of the Corporation may be called only by the Board of Directors acting pursuant to a resolution approved by the affirmative vote of a majority of the Directors then in office. Only those matters set forth in the notice of the special meeting may be considered or acted upon at a special meeting of stockholders of the Corporation.

ARTICLE VI

DIRECTORS

        1.     General.     The business and affairs of the Corporation shall be managed by or under the direction of the Board of Directors except as otherwise provided herein or required by law.

        2.     Election of Directors.     Election of Directors need not be by written ballot unless the By-laws of the Corporation (the "By-laws") shall so provide.

        3.     Number of Directors; Term of Office.     The number of Directors of the Corporation shall be fixed solely and exclusively by resolution duly adopted from time to time by the Board of Directors. The Directors, other than those who may be elected by the holders of any series of Undesignated Preferred Stock, shall be classified, with respect to the term for which they severally hold office, into three classes, as nearly equal in number as reasonably possible. The Directors of the Corporation initially will be assigned to be Class I Directors, Class II Directors and Class III Directors of the Corporation in accordance with a resolution or resolutions adopted by the Board of Directors. The initial Class I Directors shall serve for a term expiring at the annual meeting of stockholders to be held in 2005, the initial Class II Directors shall serve for a term expiring at the annual meeting of stockholders to be held in 2006, and the initial Class III Directors shall serve for a term expiring at the annual meeting of stockholders to be held in 2007. At each annual meeting of stockholders, Directors elected to succeed those Directors whose terms expire shall be elected for a term of office to expire at the third succeeding annual meeting of stockholders after their election. Notwithstanding the foregoing, the Directors elected to each class shall hold office until their successors are duly elected and qualified or until their earlier resignation or removal.

        Notwithstanding the foregoing, whenever, pursuant to the provisions of Article IV of this Certificate, the holders of any one or more series of Undesignated Preferred Stock shall have the right, voting separately as a series or together with holders of other such series, to elect Directors at an annual or special meeting of stockholders, the election, term of office, filling of vacancies and other features of such directorships shall be governed by the terms of this Certificate and any certificate of designations applicable thereto.

        4.     Vacancies.     Subject to the rights, if any, of the holders of any series of Undesignated Preferred Stock to elect Directors and to fill vacancies in the Board of Directors relating thereto, any and all vacancies in the Board of Directors, however occurring, including, without limitation, by reason of an increase in size of the Board of Directors, or the death, resignation, disqualification or removal of a Director, shall be filled solely and exclusively by the affirmative vote of a majority of the remaining

3



Directors then in office, even if less than a quorum of the Board of Directors, and not by the stockholders. Any Director appointed in accordance with the preceding sentence shall hold office for the remainder of the full term of the class of Directors in which the new directorship was created or the vacancy occurred and until such Director's successor shall have been duly elected and qualified or until his or her earlier resignation or removal. Subject to the rights, if any, of the holders of any series of Undesignated Preferred Stock to elect Directors, when the number of Directors is increased or decreased, the Board of Directors shall, subject to Article VI.3 hereof, determine the class or classes to which the increased or decreased number of Directors shall be apportioned; provided, however, that no decrease in the number of Directors shall shorten the term of any incumbent Director. In the event of a vacancy in the Board of Directors, the remaining Directors, except as otherwise provided by law, shall exercise the powers of the full Board of Directors until the vacancy is filled.

        5.     Removal.     Subject to the rights, if any, of any series of Undesignated Preferred Stock to elect Directors and to remove any Director whom the holders of any such stock have the right to elect, any Director (including persons elected by Directors to fill vacancies in the Board of Directors) may be removed from office (i) only with cause and (ii) only by the affirmative vote of the holders of 75% or more of the shares then entitled to vote at an election of Directors. At least forty-five (45) days prior to any meeting of stockholders at which it is proposed that any Director be removed from office, written notice of such proposed removal and the alleged grounds thereof shall be sent to the Director whose removal will be considered at the meeting.

ARTICLE VII

LIMITATION OF LIABILITY

        A Director of the Corporation shall not be personally liable to the Corporation or its stockholders for monetary damages for breach of fiduciary duty as a Director, except for liability (a) for any breach of the Director's duty of loyalty to the Corporation or its stockholders, (b) for acts or omissions not in good faith or which involve intentional misconduct or a knowing violation of law, (c) under Section 174 of the DGCL or (d) for any transaction from which the Director derived an improper personal benefit. If the DGCL is amended after the effective date of this Certificate to authorize corporate action further eliminating or limiting the personal liability of Directors, then the liability of a Director of the Corporation shall be eliminated or limited to the fullest extent permitted by the DGCL, as so amended.

        Any repeal or modification of this Article VII by either of (i) the stockholders of the Corporation or (ii) an amendment to the DGCL, shall not adversely affect any right or protection existing at the time of such repeal or modification with respect to any acts or omissions occurring before such repeal or modification of a person serving as a Director at the time of such repeal or modification.

ARTICLE VIII

AMENDMENT OF BY-LAWS

        1.     Amendment by Directors.     Except as otherwise provided by law, the By-laws of the Corporation may be amended or repealed by the Board of Directors by the affirmative vote of a majority of the Directors then in office.

        2.     Amendment by Stockholders.     The By-laws of the Corporation may be amended or repealed at any annual meeting of stockholders, or special meeting of stockholders called for such purpose as provided in the By-laws, by the affirmative vote of at least 75% of the outstanding shares entitled to vote on such amendment or repeal, voting together as a single class; provided, however, that if the Board of Directors recommends that stockholders approve such amendment or repeal at such meeting

4



of stockholders, such amendment or repeal shall only require the affirmative vote of the majority of the outstanding shares entitled to vote on such amendment or repeal, voting together as a single class.

ARTICLE IX

AMENDMENT OF CERTIFICATE OF INCORPORATION

        The Corporation reserves the right to amend or repeal this Certificate in the manner now or hereafter prescribed by statute and this Certificate, and all rights conferred upon stockholders herein are granted subject to this reservation. Whenever any vote of the holders of voting stock is required to amend or repeal any provision of this Certificate, and in addition to any other vote of holders of voting stock that is required by this Certificate or by law, such amendment or repeal shall require the affirmative vote of the majority of the outstanding shares entitled to vote on such amendment or repeal, and the affirmative vote of the majority of the outstanding shares of each class entitled to vote thereon as a class, at a duly constituted meeting of stockholders called expressly for such purpose; provided, however, that the affirmative vote of not less than 75% of the outstanding shares entitled to vote on such amendment or repeal, and the affirmative vote of not less than 75% of the outstanding shares of each class entitled to vote thereon as a class, shall be required to amend or repeal any provision of Article V, Article VI, Article VII, Article VIII or Article IX of this Certificate.

[End of Text]

5


        THIS THIRD AMENDED AND RESTATED CERTIFICATE OF INCORPORATION is executed as of this 27 th day of July, 2004.

    NEUROMETRIX, INC.

 

 

By:

/s/  
SHAI N. GOZANI, M.D., PH.D.       
Shai N. Gozani, M.D., Ph.D.
President and Chief Executive Officer

6




QuickLinks


QuickLinks -- Click here to rapidly navigate through this document


Exhibit 4.2

SECOND AMENDED AND RESTATED
BY-LAWS
OF
NEUROMETRIX, INC.
(the "Corporation")

ARTICLE I

Stockholders

        SECTION 1.     Annual Meeting.     The annual meeting of stockholders (any such meeting being referred to in these By-laws as an "Annual Meeting") shall be held at the hour, date and place within or without the United States which is fixed by the Board of Directors, which time, date and place may subsequently be changed at any time by vote of the Board of Directors. If no Annual Meeting has been held for a period of thirteen months after the Corporation's last Annual Meeting, a special meeting in lieu thereof may be held, and such special meeting shall have, for the purposes of these By-laws or otherwise, all the force and effect of an Annual Meeting. Any and all references hereafter in these By-laws to an Annual Meeting or Annual Meetings also shall be deemed to refer to any special meeting(s) in lieu thereof.

        SECTION 2.     Notice of Stockholder Business and Nominations.     

        (a)    Annual Meetings of Stockholders.


        (b)    General.

2


        SECTION 3.     Special Meetings.     Except as otherwise required by statute and subject to the rights, if any, of the holders of any series of Undesignated Preferred Stock, special meetings of the stockholders of the Corporation may be called only by the Board of Directors acting pursuant to a resolution approved by the affirmative vote of a majority of the Directors then in office. Only those matters set forth in the notice of the special meeting may be considered or acted upon at a special meeting of stockholders of the Corporation.

        SECTION 4.     Notice of Meetings; Adjournments.     A notice of each Annual Meeting stating the hour, date and place, if any, of such Annual Meeting shall be given not less than ten (10) days nor more than sixty (60) days before the Annual Meeting, to each stockholder entitled to vote thereat by delivering such notice to such stockholder or by mailing it, postage prepaid, addressed to such stockholder at the address of such stockholder as it appears on the Corporation's stock transfer books.

        Notice of all special meetings of stockholders shall be given in the same manner as provided for Annual Meetings, except that the notice of all special meetings shall state the purpose or purposes for which the meeting has been called.

        Notice of an Annual Meeting or special meeting of stockholders need not be given to a stockholder if a waiver of notice is executed before or after such meeting by such stockholder or if such stockholder attends such meeting, unless such attendance was for the express purpose of objecting at the beginning of the meeting to the transaction of any business because the meeting was not lawfully called or convened.

        The Board of Directors may postpone and reschedule any previously scheduled Annual Meeting or special meeting of stockholders and any record date with respect thereto, regardless of whether any notice or public disclosure with respect to any such meeting has been sent or made pursuant to Section 2 of this Article I of these By-laws or otherwise. In no event shall the public announcement of an adjournment, postponement or rescheduling of any previously scheduled meeting of stockholders commence a new time period for the giving of a stockholder's notice under Section 2 of this Article I of these By-laws.

        When any meeting is convened, the presiding officer may adjourn the meeting if (a) no quorum is present for the transaction of business, (b) the Board of Directors determines that adjournment is necessary or appropriate to enable the stockholders to consider fully information which the Board of Directors determines has not been made sufficiently or timely available to stockholders, or (c) the Board of Directors determines that adjournment is otherwise in the best interests of the Corporation. When any Annual Meeting or special meeting of stockholders is adjourned to another hour, date or place, notice need not be given of the adjourned meeting other than an announcement at the meeting at which the adjournment is taken of the hour, date and place, if any, to which the meeting is adjourned and the means of remote communications, if any, by which stockholders and proxyholders may be deemed to be present in person and vote at such adjourned meeting; provided, however, that if the adjournment is for more than 30 days, or if after the adjournment a new record date is fixed for the adjourned meeting, notice of the adjourned meeting and the means of remote communications, if any, by which stockholders and proxyholders may be deemed to be present in person and vote at such adjourned meeting shall be given to each stockholder of record entitled to vote thereat and each stockholder who, by law or under the Certificate of Incorporation of the Corporation (as the same may hereafter be amended and/or restated, the "Certificate") or these By-laws, is entitled to such notice.

        SECTION 5.     Quorum.     A majority of the shares entitled to vote, present in person or represented by proxy, shall constitute a quorum at any meeting of stockholders. If less than a quorum

3



is present at a meeting, the holders of voting stock representing a majority of the voting power present at the meeting or the presiding officer may adjourn the meeting from time to time, and the meeting may be held as adjourned without further notice, except as provided in Section 5 of this Article I. At such adjourned meeting at which a quorum is present, any business may be transacted which might have been transacted at the meeting as originally noticed. The stockholders present at a duly constituted meeting may continue to transact business until adjournment, notwithstanding the withdrawal of enough stockholders to leave less than a quorum.

        SECTION 6.     Voting and Proxies.     Stockholders shall have one vote for each share of stock entitled to vote owned by them of record according to the stock ledger of the Corporation, unless otherwise provided by law or by the Certificate. Stockholders may vote either (i) in person, (ii) by written proxy or (iii) by a transmission permitted by §212(c) of the Delaware General Corporation Law ("DGCL"). Any copy, facsimile telecommunication or other reliable reproduction of the writing or transmission permitted by §212(c) of the DGCL may be substituted for or used in lieu of the original writing or transmission for any and all purposes for which the original writing or transmission could be used, provided that such copy, facsimile telecommunication or other reproduction shall be a complete reproduction of the entire original writing or transmission. Proxies shall be filed in accordance with the procedures established for the meeting of stockholders. Except as otherwise limited therein or as otherwise provided by law, proxies authorizing a person to vote at a specific meeting shall entitle the persons authorized thereby to vote at any adjournment of such meeting, but they shall not be valid after final adjournment of such meeting. A proxy with respect to stock held in the name of two or more persons shall be valid if executed by or on behalf of any one of them unless at or prior to the exercise of the proxy the Corporation receives a specific written notice to the contrary from any one of them.

        SECTION 7.     Action at Meeting.     When a quorum is present at any meeting of stockholders, any matter before any such meeting (other than an election of a director or directors) shall be decided by a majority of the votes properly cast for and against such matter, except where a larger vote is required by law, by the Certificate or by these By-laws. Any election of directors by stockholders shall be determined by a plurality of the votes properly cast on the election of directors. The Corporation shall not directly or indirectly vote any shares of its own stock; provided, however, that the Corporation may vote shares which it holds in a fiduciary capacity to the extent permitted by law.

        SECTION 8.     Stockholder Lists.     The Secretary or an Assistant Secretary (or the Corporation's transfer agent or other person authorized by these By-laws or by law) shall prepare and make, at least 10 days before every Annual Meeting or special meeting of stockholders, a complete list of the stockholders entitled to vote at the meeting, arranged in alphabetical order, and showing the address of each stockholder and the number of shares registered in the name of each stockholder. Such list shall be open to the examination of any stockholder, for a period of at least ten (10) days prior to the meeting in the manner provided by law. The list shall also be open to the examination of any stockholder during the whole time of the meeting as provided by law.

        SECTION 9.     Presiding Officer.     The Chairman of the Board, if one is elected, or if not elected or in his or her absence, the President, shall preside at all Annual Meetings or special meetings of stockholders and shall have the power, among other things, to adjourn such meeting at any time and from time to time, subject to Sections 5 and 6 of this Article I. The order of business and all other matters of procedure at any meeting of the stockholders shall be determined by the presiding officer.

        SECTION 10.     Inspectors of Elections.     The Corporation shall, in advance of any meeting of stockholders, appoint one or more inspectors to act at the meeting and make a written report thereof. The Corporation may designate one or more persons as alternate inspectors to replace any inspector who fails to act. If no inspector or alternate is able to act at a meeting of stockholders, the presiding officer shall appoint one or more inspectors to act at the meeting. Any inspector may, but need not, be

4



an officer, employee or agent of the Corporation. Each inspector, before entering upon the discharge of his or her duties, shall take and sign an oath faithfully to execute the duties of inspector with strict impartiality and according to the best of his or her ability. The inspectors shall perform such duties as are required by the DGCL, including the counting of all votes and ballots. The inspectors may appoint or retain other persons or entities to assist the inspectors in the performance of the duties of the inspectors. The presiding officer may review all determinations made by the inspectors, and in so doing the presiding officer shall be entitled to exercise his or her sole judgment and discretion and he or she shall not be bound by any determinations made by the inspectors. All determinations by the inspectors and, if applicable, the presiding officer, shall be subject to further review by any court of competent jurisdiction.

ARTICLE II

Directors

        SECTION 1.     Powers.     The business and affairs of the Corporation shall be managed by or under the direction of the Board of Directors except as otherwise provided by the Certificate or required by law.

        SECTION 2.     Number and Terms.     The number of directors of the Corporation shall be fixed solely and exclusively by resolution duly adopted from time to time by the Board of Directors. The directors shall hold office in the manner provided in the Certificate.

        SECTION 3.     Qualification.     No director need be a stockholder of the Corporation.

        SECTION 4.     Vacancies.     Vacancies in the Board of Directors shall be filled in the manner provided in the Certificate.

        SECTION 5.     Removal.     Directors may be removed from office in the manner provided in the Certificate.

        SECTION 6.     Resignation.     A director may resign at any time by giving written notice to the Chairman of the Board, if one is elected, the President or the Secretary. A resignation shall be effective upon receipt, unless the resignation otherwise provides.

        SECTION 7.     Regular Meetings.     The regular annual meeting of the Board of Directors shall be held, without notice other than this Section 7, on the same date and at the same place as the Annual Meeting following the close of such meeting of stockholders. Other regular meetings of the Board of Directors may be held at such hour, date and place as the Board of Directors may by resolution from time to time determine and publicize by means of reasonable notice given to any director who is not present at the meeting at which such resolution is adopted.

        SECTION 8.     Special Meetings.     Special meetings of the Board of Directors may be called, orally or in writing, by or at the request of a majority of the directors, the Chairman of the Board, if one is elected, or the President. The person calling any such special meeting of the Board of Directors may fix the hour, date and place thereof.

        SECTION 9.     Notice of Meetings.     Notice of the hour, date and place of all special meetings of the Board of Directors shall be given to each director by the Secretary or an Assistant Secretary, or in case of the death, absence, incapacity or refusal of such persons, by the Chairman of the Board, if one is elected, or the President or such other officer designated by the Chairman of the Board, if one is elected, or the President. Notice of any special meeting of the Board of Directors shall be given to each director in person, by telephone, or by facsimile, electronic mail or other form of electronic communication, sent to his or her business or home address, at least 24 hours in advance of the meeting, or by written notice mailed to his or her business or home address, at least 48 hours in advance of the meeting. Such notice shall be deemed to be delivered when hand delivered to such

5



address, read to such director by telephone, deposited in the mail so addressed, with postage thereon prepaid if mailed, dispatched or transmitted if faxed, telexed or telecopied, or when delivered to the telegraph company if sent by telegram.

        A written waiver of notice signed before or after a meeting by a director and filed with the records of the meeting shall be deemed to be equivalent to notice of the meeting. The attendance of a director at a meeting shall constitute a waiver of notice of such meeting, except where a director attends a meeting for the express purpose of objecting at the beginning of the meeting to the transaction of any business because such meeting is not lawfully called or convened. Except as otherwise required by law, by the Certificate or by these By-laws, neither the business to be transacted at, nor the purpose of, any meeting of the Board of Directors need be specified in the notice or waiver of notice of such meeting.

        SECTION 10.     Quorum.     At any meeting of the Board of Directors, a majority of the total number of directors shall constitute a quorum for the transaction of business, but if less than a quorum is present at a meeting, a majority of the directors present may adjourn the meeting from time to time, and the meeting may be held as adjourned without further notice, except as provided in Section 9 of this Article II. Any business which might have been transacted at the meeting as originally noticed may be transacted at such adjourned meeting at which a quorum is present. For purposes of this section, the total number of directors includes any unfilled vacancies on the Board of Directors.

        SECTION 11.     Action at Meeting.     At any meeting of the Board of Directors at which a quorum is present, the vote of a majority of the directors present shall constitute action by the Board of Directors, unless otherwise required by law, by the Certificate or by these By-laws.

        SECTION 12.     Action by Consent.     Any action required or permitted to be taken at any meeting of the Board of Directors may be taken without a meeting if all members of the Board of Directors consent thereto in writing or by electronic transmission and the writing or writings or electronic transmission or transmissions are filed with the records of the meetings of the Board of Directors. Such filing shall be in paper form if the minutes are maintained in paper form and shall be in electronic form if the minutes are maintained in electronic form. Such consent shall be treated as a resolution of the Board of Directors for all purposes.

        SECTION 13.     Manner of Participation.     Directors may participate in meetings of the Board of Directors by means of conference telephone or other communications equipment by means of which all directors participating in the meeting can hear each other, and participation in a meeting in accordance herewith shall constitute presence in person at such meeting for purposes of these By-laws.

        SECTION 14.     Committees.     The Board of Directors, by vote of a majority of the directors then in office, may designate from its number one or more committees, including, without limitation, an Executive Committee, a Compensation Committee, a Stock Option Committee, an Audit Committee and a Nominating Committee, and may delegate thereto some or all of its powers except those which by law, by the Certificate or by these By-laws may not be delegated. Except as the Board of Directors may otherwise determine, any such committee may make rules for the conduct of its business, but unless otherwise provided by the Board of Directors or in such rules, its business shall be conducted so far as possible in the same manner as is provided by these By-laws for the Board of Directors. All members of such committees shall hold such offices at the pleasure of the Board of Directors. The Board of Directors may abolish any such committee at any time. Any committee to which the Board of Directors delegates any of its powers or duties shall keep records of its meetings and shall report its action to the Board of Directors.

        SECTION 15.     Compensation of Directors.     Directors shall receive such compensation for their services as shall be determined by a majority of the Board of Directors, or a designated committee thereof, provided that directors who are serving the Corporation as employees and who receive

6



compensation for their services as such, shall not receive any salary or other compensation for their services as directors of the Corporation.

ARTICLE III

Officers

        SECTION 1.     Enumeration.     The officers of the Corporation shall consist of a President, a Treasurer, a Secretary and such other officers, including, without limitation, a Chairman of the Board of Directors, a Chief Executive Officer and one or more Vice Presidents (including Executive Vice Presidents or Senior Vice Presidents), Assistant Vice Presidents, Assistant Treasurers and Assistant Secretaries, as the Board of Directors may determine.

        SECTION 2.     Election.     At the regular annual meeting of the Board of Directors following the Annual Meeting, the Board of Directors shall elect the President, the Treasurer and the Secretary. Other officers may be elected by the Board of Directors at such regular annual meeting of the Board of Directors or at any other regular or special meeting.

        SECTION 3.     Qualification.     No officer need be a stockholder or a director. Any person may occupy more than one office of the Corporation at any time. Any officer may be required by the Board of Directors to give bond for the faithful performance of his or her duties in such amount and with such sureties as the Board of Directors may determine.

        SECTION 4.     Tenure.     Except as otherwise provided by the Certificate or by these By-laws, each of the officers of the Corporation shall hold office until the regular annual meeting of the Board of Directors following the next Annual Meeting and until his or her successor is elected and qualified or until his or her earlier resignation or removal.

        SECTION 5.     Resignation.     Any officer may resign by delivering his or her written resignation to the Corporation addressed to the President or the Secretary, and such resignation shall be effective upon receipt unless it is specified to be effective at some other time or upon the happening of some other event.

        SECTION 6.     Removal.     Except as otherwise provided by law, the Board of Directors may remove any officer with or without cause by the affirmative vote of a majority of the directors then in office.

        SECTION 7.     Absence or Disability.     In the event of the absence or disability of any officer, the Board of Directors may designate another officer to act temporarily in place of such absent or disabled officer.

        SECTION 8.     Vacancies.     Any vacancy in any office may be filled for the unexpired portion of the term by the Board of Directors.

        SECTION 9.     President.     The President shall, subject to the direction of the Board of Directors, have general supervision and control of the Corporation's business. If there is no Chairman of the Board or if he or she is absent, the President shall preside, when present, at all meetings of stockholders and of the Board of Directors. The President shall have such other powers and perform such other duties as the Board of Directors may from time to time designate.

        SECTION 10.     Chairman of the Board.     The Chairman of the Board, if one is elected, shall preside, when present, at all meetings of the stockholders and of the Board of Directors. The Chairman of the Board shall have such other powers and shall perform such other duties as the Board of Directors may from time to time designate.

        SECTION 11.     Chief Executive Officer.     The Chief Executive Officer, if one is elected, shall have such powers and shall perform such duties as the Board of Directors may from time to time designate.

7



        SECTION 12.     Vice Presidents and Assistant Vice Presidents.     Any Vice President (including any Executive Vice President or Senior Vice President) and any Assistant Vice President shall have such powers and shall perform such duties as the Board of Directors or the Chief Executive Officer may from time to time designate.

        SECTION 13.     Treasurer and Assistant Treasurers.     The Treasurer shall, subject to the direction of the Board of Directors and except as the Board of Directors or the Chief Executive Officer may otherwise provide, have general charge of the financial affairs of the Corporation and shall cause to be kept accurate books of account. The Treasurer shall have custody of all funds, securities, and valuable documents of the Corporation. He or she shall have such other duties and powers as may be designated from time to time by the Board of Directors or the Chief Executive Officer.

        Any Assistant Treasurer shall have such powers and perform such duties as the Board of Directors or the Chief Executive Officer may from time to time designate.

        SECTION 14.     Secretary and Assistant Secretaries.     The Secretary shall record all the proceedings of the meetings of the stockholders and the Board of Directors (including committees of the Board) in books kept for that purpose. In his or her absence from any such meeting, a temporary secretary chosen at the meeting shall record the proceedings thereof. The Secretary shall have charge of the stock ledger (which may, however, be kept by any transfer or other agent of the Corporation). The Secretary shall have custody of the seal of the Corporation, and the Secretary, or an Assistant Secretary, shall have authority to affix it to any instrument requiring it, and, when so affixed, the seal may be attested by his or her signature or that of an Assistant Secretary. The Secretary shall have such other duties and powers as may be designated from time to time by the Board of Directors or the Chief Executive Officer. In the absence of the Secretary, any Assistant Secretary may perform his or her duties and responsibilities.

        Any Assistant Secretary shall have such powers and perform such duties as the Board of Directors or the Chief Executive Officer may from time to time designate.

        SECTION 15.     Other Powers and Duties.     Subject to these By-laws and to such limitations as the Board of Directors may from time to time prescribe, the officers of the Corporation shall each have such powers and duties as generally pertain to their respective offices, as well as such powers and duties as from time to time may be conferred by the Board of Directors or the Chief Executive Officer.

ARTICLE IV

Capital Stock

        SECTION 1.     Certificates of Stock.     Each stockholder shall be entitled to a certificate of the capital stock of the Corporation in such form as may from time to time be prescribed by the Board of Directors. Such certificate shall be signed by the Chairman of the Board of Directors, the President or a Vice President and by the Treasurer or an Assistant Treasurer, or the Secretary or an Assistant Secretary. The Corporation seal and the signatures by the Corporation's officers, the transfer agent or the registrar may be facsimiles. In case any officer, transfer agent or registrar who has signed or whose facsimile signature has been placed on such certificate shall have ceased to be such officer, transfer agent or registrar before such certificate is issued, it may be issued by the Corporation with the same effect as if he or she were such officer, transfer agent or registrar at the time of its issue. Every certificate for shares of stock which are subject to any restriction on transfer and every certificate issued when the Corporation is authorized to issue more than one class or series of stock shall contain such legend with respect thereto as is required by law.

        SECTION 2.     Transfers.     Subject to any restrictions on transfer and unless otherwise provided by the Board of Directors, shares of stock may be transferred only on the books of the Corporation by the surrender to the Corporation or its transfer agent of the certificate theretofore properly endorsed or

8



accompanied by a written assignment or power of attorney properly executed, with transfer stamps (if necessary) affixed, and with such proof of the authenticity of signature as the Corporation or its transfer agent may reasonably require.

        SECTION 3.     Record Holders.     Except as may otherwise be required by law, by the Certificate or by these By-laws, the Corporation shall be entitled to treat the record holder of stock as shown on its books as the owner of such stock for all purposes, including the payment of dividends and the right to vote with respect thereto, regardless of any transfer, pledge or other disposition of such stock, until the shares have been transferred on the books of the Corporation in accordance with the requirements of these By-laws.

        SECTION 4.     Record Date.     In order that the Corporation may determine the stockholders entitled to notice of or to vote at any meeting of stockholders or any adjournment thereof or entitled to receive payment of any dividend or other distribution or allotment of any rights, or entitled to exercise any rights in respect of any change, conversion or exchange of stock or for the purpose of any other lawful action, the Board of Directors may fix a record date, which record date shall not precede the date upon which the resolution fixing the record date is adopted by the Board of Directors, and which record date: (a) in the case of determination of stockholders entitled to vote at any meeting of stockholders, shall, unless otherwise required by law, not be more than sixty nor less than ten days before the date of such meeting and (b) in the case of any other action, shall not be more than sixty days prior to such other action. If no record date is fixed: (i) the record date for determining stockholders entitled to notice of or to vote at a meeting of stockholders shall be at the close of business on the day next preceding the day on which notice is given, or, if notice is waived, at the close of business on the day next preceding the day on which the meeting is held and (ii) the record date for determining stockholders for any other purpose shall be at the close of business on the day on which the Board of Directors adopts the resolution relating thereto.

        5.     Replacement of Certificates.     In case of the alleged loss, destruction or mutilation of a certificate of stock, a duplicate certificate may be issued in place thereof, upon such terms as the Board of Directors may prescribe.

ARTICLE V

Indemnification

        SECTION 1.     Definitions.     For purposes of this Article:

        (a)   "Corporate Status" describes the status of a person who is serving or has served (i) as a Director of the Corporation, (ii) as an Officer of the Corporation, or (iii) as a director, partner, trustee, officer, employee or agent of any other corporation, partnership, joint venture, trust, employee benefit plan or other enterprise which such person is or was serving at the request of the Corporation. For purposes of this Section 1(a), an Officer or Director of the Corporation who is serving or has served as a director, partner, trustee, officer, employee or agent of a Subsidiary shall be deemed to be serving at the request of the Corporation. Notwithstanding the foregoing, "Corporate Status" shall not include the status of a person who is serving or has served as a director, officer, employee or agent of a constituent corporation absorbed in a merger or consolidation transaction with the Corporation with respect to such person's activities prior to said transaction, unless specifically authorized by the Board of Directors or the stockholders of the Corporation;

        (b)   "Director" means any person who serves or has served the Corporation as a director on the Board of Directors of the Corporation;

        (c)   "Disinterested Director" means, with respect to each Proceeding in respect of which indemnification is sought hereunder, a Director of the Corporation who is not and was not a party to such Proceeding;

9



        (d)   "Expenses" means all reasonable attorneys' fees, retainers, court costs, transcript costs, fees of expert witnesses, private investigators and professional advisors (including, without limitation, accountants and investment bankers), travel expenses, duplicating costs, printing and binding costs, costs of preparation of demonstrative evidence and other courtroom presentation aids and devices, costs incurred in connection with document review, organization, imaging and computerization, telephone charges, postage, delivery service fees, and all other disbursements, costs or expenses of the type customarily incurred in connection with prosecuting, defending, preparing to prosecute or defend, investigating, being or preparing to be a witness in, settling or otherwise participating in, a Proceeding;

        (e)   "Non-Officer Employee" means any person who serves or has served as an employee or agent of the Corporation, but who is not or was not a Director or Officer;

        (f)    "Officer" means any person who serves or has served the Corporation as an officer appointed by the Board of Directors of the Corporation;

        (g)   "Proceeding" means any threatened, pending or completed action, suit, arbitration, alternate dispute resolution mechanism, inquiry, investigation, administrative hearing or other proceeding, whether civil, criminal, administrative, arbitrative or investigative; and

        (h)   "Subsidiary" shall mean any corporation, partnership, limited liability company, joint venture, trust or other entity of which the Corporation owns (either directly or through or together with another Subsidiary of the Corporation) either (i) a general partner, managing member or other similar interest or (ii) (A) 50% or more of the voting power of the voting capital equity interests of such corporation, partnership, limited liability company, joint venture or other entity, or (B) 50% or more of the outstanding voting capital stock or other voting equity interests of such corporation, partnership, limited liability company, joint venture or other entity.

        SECTION 2.     Indemnification of Directors and Officers.     Subject to the operation of Section 4 of this Article V of these By-laws, each Director and Officer shall be indemnified and held harmless by the Corporation to the fullest extent authorized by the DGCL, as the same exists or may hereafter be amended (but, in the case of any such amendment, only to the extent that such amendment permits the Corporation to provide broader indemnification rights than such law permitted the Corporation to provide prior to such amendment) against any and all Expenses, judgments, penalties, fines and amounts reasonably paid in settlement that are incurred by such Director or Officer or on such Director's or Officer's behalf in connection with any threatened, pending or completed Proceeding or any claim, issue or matter therein, which such Director or Officer is, or is threatened to be made, a party to or participant in by reason of such Director's or Officer's Corporate Status, if such Director or Officer acted in good faith and in a manner such Director or Officer reasonably believed to be in or not opposed to the best interests of the Corporation and, with respect to any criminal proceeding, had no reasonable cause to believe his or her conduct was unlawful. The rights of indemnification provided by this Section 2 shall continue as to a Director or Officer after he or she has ceased to be a Director or Officer and shall inure to the benefit of his or her heirs, executors, administrators and personal representatives. Notwithstanding the foregoing, the Corporation shall indemnify any Director or Officer seeking indemnification in connection with a Proceeding initiated by such Director or Officer only if such Proceeding was authorized by the Board of Directors of the Corporation, unless such Proceeding was brought to enforce an Officer or Director's rights to indemnification or, in the case of Directors, advancement of Expenses under these By-laws in accordance with the provisions set forth herein.

        SECTION 3.     Indemnification of Non-Officer Employees.     Subject to the operation of Section 4 of this Article V of these By-laws, each Non-Officer Employee may, in the discretion of the Board of Directors of the Corporation, be indemnified by the Corporation to the fullest extent authorized by the DGCL, as the same exists or may hereafter be amended, against any or all Expenses, judgments, penalties, fines and amounts reasonably paid in settlement that are incurred by such Non-Officer Employee or on such Non-Officer Employee's behalf in connection with any threatened, pending or

10



completed Proceeding, or any claim, issue or matter therein, which such Non-Officer Employee is, or is threatened to be made, a party to or participant in by reason of such Non-Officer Employee's Corporate Status, if such Non-Officer Employee acted in good faith and in a manner such Non-Officer Employee reasonably believed to be in or not opposed to the best interests of the Corporation and, with respect to any criminal proceeding, had no reasonable cause to believe his or her conduct was unlawful. The rights of indemnification provided by this Section 3 shall exist as to a Non-Officer Employee after he or she has ceased to be a Non-Officer Employee and shall inure to the benefit of his or her heirs, personal representatives, executors and administrators. Notwithstanding the foregoing, the Corporation may indemnify any Non-Officer Employee seeking indemnification in connection with a Proceeding initiated by such Non-Officer Employee only if such Proceeding was authorized by the Board of Directors of the Corporation.

        SECTION 4.     Good Faith.     Unless ordered by a court, no indemnification shall be provided pursuant to this Article V to a Director, to an Officer or to a Non-Officer Employee unless a determination shall have been made that such person acted in good faith and in a manner such person reasonably believed to be in or not opposed to the best interests of the Corporation and, with respect to any criminal Proceeding, such person had no reasonable cause to believe his or her conduct was unlawful. Such determination shall be made by (a) a majority vote of the Disinterested Directors, even though less than a quorum of the Board of Directors, (b) a committee comprised of Disinterested Directors, such committee having been designated by a majority vote of the Disinterested Directors (even though less than a quorum), (c) if there are no such Disinterested Directors, or if a majority of Disinterested Directors so directs, by independent legal counsel in a written opinion, or (d) by the stockholders of the Corporation.

        SECTION 5.     Advancement of Expenses to Directors Prior to Final Disposition.     

        (a)   The Corporation shall advance all Expenses incurred by or on behalf of any Director in connection with any Proceeding in which such Director is involved by reason of such Director's Corporate Status within ten (10) days after the receipt by the Corporation of a written statement from such Director requesting such advance or advances from time to time, whether prior to or after final disposition of such Proceeding. Such statement or statements shall reasonably evidence the Expenses incurred by such Director and shall be preceded or accompanied by an undertaking by or on behalf of such Director to repay any Expenses so advanced if it shall ultimately be determined that such Director is not entitled to be indemnified against such Expenses. Notwithstanding the foregoing, the Corporation shall advance all Expenses incurred by or on behalf of any Director seeking advancement of expenses hereunder in connection with a Proceeding initiated by such Director only if such Proceeding was (i) authorized by the Board of Directors of the Corporation, or (ii) brought to enforce Director's rights to indemnification or advancement of Expenses under these By-laws.

        (b)   If a claim for advancement of Expenses hereunder by a Director is not paid in full by the Corporation within 10 days after receipt by the Corporation of documentation of Expenses and the required undertaking, such Director may at any time thereafter bring suit against the Corporation to recover the unpaid amount of the claim and if successful in whole or in part, such Director shall also be entitled to be paid the expenses of prosecuting such claim. The failure of the Corporation (including its Board of Directors or any committee thereof, independent legal counsel, or stockholders) to make a determination concerning the permissibility of such advancement of Expenses under this Article V shall not be a defense to the action and shall not create a presumption that such advancement is not permissible. The burden of proving that a Director is not entitled to an advancement of expenses shall be on the Corporation.

        (c)   In any suit brought by the Corporation to recover an advancement of expenses pursuant to the terms of an undertaking, the Corporation shall be entitled to recover such expenses upon a final

11



adjudication that the Director has not met any applicable standard for indemnification set forth in the DGCL.

        SECTION 6.     Advancement of Expenses to Officers and Non-Officer Employees Prior to Final Disposition.     

        (a)   The Corporation may, at the discretion of the Board of Directors of the Corporation, advance any or all Expenses incurred by or on behalf of any Officer and Non-Officer Employee in connection with any Proceeding in which such is involved by reason of the Corporate Status of such Officer or Non-Officer Employee upon the receipt by the Corporation of a statement or statements from such Officer or Non-Officer Employee requesting such advance or advances from time to time, whether prior to or after final disposition of such Proceeding. Such statement or statements shall reasonably evidence the Expenses incurred by such Officer and Non-Officer Employee and shall be preceded or accompanied by an undertaking by or on behalf of such to repay any Expenses so advanced if it shall ultimately be determined that such Officer or Non-Officer Employee is not entitled to be indemnified against such Expenses.

        (b)   In any suit brought by the Corporation to recover an advancement of expenses pursuant to the terms of an undertaking, the Corporation shall be entitled to recover such expenses upon a final adjudication that the Officer or Non-Officer Employee has not met any applicable standard for indemnification set forth in the DGCL.

        SECTION 7.     Contractual Nature of Rights.     

        (a)   The foregoing provisions of this Article V shall be deemed to be a contract between the Corporation and each Director and Officer entitled to the benefits hereof at any time while this Article V is in effect, and any repeal or modification thereof shall not affect any rights or obligations then existing with respect to any state of facts then or theretofore existing or any Proceeding theretofore or thereafter brought based in whole or in part upon any such state of facts.

        (b)   If a claim for indemnification hereunder by a Director or Officer is not paid in full by the Corporation within 60 days after receipt by the Corporation of a written claim for indemnification, such Director or Officer may at any time thereafter bring suit against the Corporation to recover the unpaid amount of the claim, and if successful in whole or in part, such Director or Officer shall also be entitled to be paid the expenses of prosecuting such claim. The failure of the Corporation (including its Board of Directors or any committee thereof, independent legal counsel, or stockholders) to make a determination concerning the permissibility of such indemnification under this Article V shall not be a defense to the action and shall not create a presumption that such indemnification is not permissible. The burden of proving that a Director or Officer is not entitled to indemnification shall be on the Corporation.

        (c)   In any suit brought by a Director or Officer to enforce a right to indemnification hereunder, it shall be a defense that such Director or Officer has not met any applicable standard for indemnification set forth in the DGCL.

        SECTION 8.     Non-Exclusivity of Rights.     The rights to indemnification and advancement of Expenses set forth in this Article V shall not be exclusive of any other right which any Director, Officer, or Non-Officer Employee may have or hereafter acquire under any statute, provision of the Certificate or these By-laws, agreement, vote of stockholders or Disinterested Directors or otherwise.

        SECTION 9.     Insurance.     The Corporation may maintain insurance, at its expense, to protect itself and any Director, Officer or Non-Officer Employee against any liability of any character asserted against or incurred by the Corporation or any such Director, Officer or Non-Officer Employee, or arising out of any such person's Corporate Status, whether or not the Corporation would have the

12



power to indemnify such person against such liability under the DGCL or the provisions of this Article V.

        SECTION 10.     Other Indemnification.     The Corporation's obligation, if any, to indemnify any person under this Article V as a result of such person serving, at the request of the Corporation, as a director, partner, trustee, officer, employee or agent of another corporation, partnership, joint venture, trust, employee benefit plan or other enterprise shall be reduced by any amount such person may collect as indemnification from such other corporation, partnership, joint venture, trust, employee benefit plan or enterprise.

ARTICLE VI

Miscellaneous Provisions

        SECTION 1.     Fiscal Year.     The fiscal year of the Corporation shall be determined by the Board of Directors.

        SECTION 2.     Seal.     The Board of Directors shall have power to adopt and alter the seal of the Corporation.

        SECTION 3.     Execution of Instruments.     All deeds, leases, transfers, contracts, bonds, notes and other obligations to be entered into by the Corporation in the ordinary course of its business without director action may be executed on behalf of the Corporation by the Chairman of the Board, if one is elected, the President or the Treasurer or any other officer, employee or agent of the Corporation as the Board of Directors or Executive Committee may authorize.

        SECTION 4.     Voting of Securities.     Unless the Board of Directors otherwise provides, the Chairman of the Board, if one is elected, the President or the Treasurer may waive notice of and act on behalf of this Corporation, or appoint another person or persons to act as proxy or attorney in fact for this Corporation with or without discretionary power and/or power of substitution, at any meeting of stockholders or shareholders of any other corporation or organization, any of whose securities are held by this Corporation.

        SECTION 5.     Resident Agent.     The Board of Directors may appoint a resident agent upon whom legal process may be served in any action or proceeding against the Corporation.

        SECTION 6.     Corporate Records.     The original or attested copies of the Certificate, By-laws and records of all meetings of the incorporators, stockholders and the Board of Directors and the stock transfer books, which shall contain the names of all stockholders, their record addresses and the amount of stock held by each, may be kept outside the State of Delaware and shall be kept at the principal office of the Corporation, at the office of its counsel or at an office of its transfer agent or at such other place or places as may be designated from time to time by the Board of Directors.

        SECTION 7.     Certificate.     All references in these By-laws to the Certificate shall be deemed to refer to the Amended and Restated Certificate of Incorporation of the Corporation, as amended and in effect from time to time.

        SECTION 8.     Amendment of By-laws.     

        (a)    Amendment by Directors. Except as provided otherwise by law, these By-laws may be amended or repealed by the Board of Directors by the affirmative vote of a majority of the directors then in office.

        (b)    Amendment by Stockholders. These By-laws may be amended or repealed at any Annual Meeting, or special meeting of stockholders called for such purpose, by the affirmative vote of at least 75% of the outstanding shares entitled to vote on such amendment or repeal, voting together as a single class; provided, however, that if the Board of Directors recommends that stockholders approve

13



such amendment or repeal at such meeting of stockholders, such amendment or repeal shall only require the affirmative vote of the majority of the outstanding shares entitled to vote on such amendment or repeal, voting together as a single class. Notwithstanding the foregoing, stockholder approval shall not be required unless mandated by the Certificate, these By-laws, or other applicable law.

        SECTION 9.     Notices.     If mailed, notice to stockholders shall be deemed given when deposited in the mail, postage prepaid, directed to the stockholder at such stockholder's address as it appears on the records of the Corporation. Without limiting the manner by which notice otherwise may be given to stockholders, any notice to stockholders may be given by electronic transmission in the manner provided in Section 232 of the DGCL.

        SECTION 10.     Waivers.     A written waiver of any notice, signed by a stockholder or director, or waiver by electronic transmission by such person, whether given before or after the time of the event for which notice is to be given, shall be deemed equivalent to the notice required to be given to such person. Neither the business nor the purpose of any meeting need be specified in such a waiver.

Adopted June 2, 2004 and effective as of July 15, 2004.

14




QuickLinks


QuickLinks -- Click here to rapidly navigate through this document


Exhibit 5.1

August 9, 2004

NeuroMetrix, Inc.
62 Fourth Avenue
Waltham, MA 02451

Re:
Legality of Securities to be Registered Under Registration Statement on Form S-8

Ladies and Gentlemen:

This opinion is furnished in connection with the registration statement on Form S-8 (the "Registration Statement") pursuant to the Securities Act of 1933, as amended (the "Securities Act"), relating to the registration of the sale of up to an aggregate of 2,218,235 shares (the "Shares") of common stock, par value $0.0001 per share, of NeuroMetrix, Inc., a Delaware corporation (the "Company"), which may be issued under the NeuroMetrix, Inc. Amended and Restated 1998 Equity Incentive Plan, as amended, the NeuroMetrix, Inc. 2004 Stock Option and Incentive Plan and the NeuroMetrix, Inc. 2004 Employee Stock Purchase Plan (the "Plans").

In connection with rendering this opinion, we have examined (i) the Third Amended and Restated Certificate of Incorporation of the Company as on file with the Secretary of State of the State of Delaware, (ii) the Second Amended and Restated By-laws of the Company, (iii) such records of the corporate proceedings of the Company as we deemed material, (iv) the Registration Statement and the exhibits thereto and the related prospectus, (v) the Plans, and (vi) such other certificates, receipts, records and documents as we considered necessary for the purposes of this opinion. In our examination, we have assumed the genuineness of all signatures, the legal capacity of natural persons, the authenticity of all documents submitted to us as certified, photostatic or facsimile copies, the authenticity of the originals of such copies and the authenticity of telephonic confirmations of public officials and others. As to facts material to our opinion, we have relied upon certificates or telephonic confirmations of public officials and certificates, documents, statements and other information of the Company or representatives or officers thereof.

We are attorneys admitted to practice in the Commonwealth of Massachusetts. We express no opinion concerning the laws of any jurisdictions other than the laws of the United States of America, the Commonwealth of Massachusetts and the Delaware General Corporation Law (which includes applicable provisions of the Delaware General Corporation Law and reported judicial decisions interpreting the Delaware General Corporation Law and applicable provisions of the Delaware Constitution), and express no opinion with respect to the blue sky or securities laws of any state, including, without limitation, Massachusetts and Delaware.

Based upon the foregoing, we are of the opinion that upon the issuance and delivery of the Shares against payment therefor in accordance with the terms of the Plans, the Shares will be legally issued, fully paid and nonassessable under the Delaware General Corporation Law.

The foregoing assumes that all requisite steps will be taken to comply with the requirements of the Securities Act and applicable requirements of state laws regulating the offer and sale of securities.

The opinions expressed herein are being furnished to you solely for your benefit in connection with the Registration Statement, and may not be used or relied upon by you for any other purpose. We hereby consent to the inclusion of this opinion as an exhibit to the Registration Statement.

Sincerely,

/s/ Goodwin Procter LLP
GOODWIN PROCTER LLP
   



QuickLinks


QuickLinks -- Click here to rapidly navigate through this document

Exhibit 23.1


CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We hereby consent to the incorporation by reference in this Registration Statement on Form S-8 of our report dated May 11, 2004, except for the fourth paragraph of Note 1, as to which the date is July 15, 2004, relating to the financial statements and financial statement schedule of NeuroMetrix, Inc. which appear in NeuroMetrix, Inc.'s Registration Statement on Form S-1 (File No. 333-115440) dated July 22, 2004.
 

/s/   PRICEWATERHOUSECOOPERS LLP       
PricewaterhouseCoopers LLP
Boston, Massachusetts
August 9, 2004

   
     



QuickLinks

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM