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                                                                        EX.10.16

                                VARIAGENICS, INC.
                              CONSULTING AGREEMENT

AGREEMENT made on April 17, 2000, by and between Alan Houston, having his
principal office at Longfield, Staines Road, Wraysbury, Berkshire TW19 5AG, UK
(the "Consultant"), and VARIAGENICS, INC., a Delaware corporation having its
principal place of business at 60 Hampshire Street, Cambridge, MA 02139 (the
"Company").

WHEREAS, the Company desires to retain the Consultant to render certain
consulting services to the Company in the field of Clinical Development and
Medical Affairs (the "Field") and Consultant desires to be so retained as a
consultant by the Company.

NOW, THEREFORE, in consideration of the premises and the mutual covenants
contained in this Agreement, and other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, the parties hereto
hereby agree as follows:

1.    Services of Consultant.

      On the terms and subject to the conditions of this Agreement, the Company
      hereby retains Consultant to render such consulting, advisory and related
      services to the Company in the Field as the Company may reasonably request
      from time to time. Consultant hereby accepts such engagement subject to
      the terms and conditions set forth herein and agrees to provide service to
      the Company as described in Exhibit A.

2.    Compensation.

      In consideration of the services to be rendered by Consultant hereunder,
      Consultant shall be entitled to receive compensation as follows:

      (a)   Consultant shall be compensated at the rate described in Exhibit A.

      (b)   Consultant shall be granted non-qualified stock options as described
            in Exhibit A.

      (c)   The Company shall reimburse Consultant for all reasonable and
            necessary expenses incurred or paid by Consultant in connection
            with, or related to, the performance of consulting services under
            this Agreement, in accordance with Company policies in effect from
            time to time.

      (d)   In the event of termination of this Agreement no further
            compensation shall be payable to Consultant hereunder.

      (e)   Termination of this Agreement shall not affect the Company's
            obligation to pay for services previously performed by Consultant or
            expenses reasonably incurred by Consultant for which Consultant is
            entitled to reimbursement hereunder.

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Consulting Agreement

3.    Term and Termination.

      The initial term of this Agreement (the "Consulting Period") shall be for
      a period of six (6) months from the date hereof and shall automatically be
      extended for an additional period or periods of six months unless either
      party shall have given to the other written notice to the contrary at
      least thirty (30) days prior to the commencement of such additional
      period; provided, however, that either the Consultant or the Company may
      terminate this Agreement, with or without cause in its sole discretion, by
      giving not less than thirty (30) days prior written notice to the other.
      The provisions of Sections 4 and 5 hereof shall survive the expiration or
      termination of this Agreement.

4.    Confidentiality and Inventions.

      (a)   Consultant shall maintain in strictest confidence, and shall use and
            disclose only as authorized by the Company, all information of a
            competitively sensitive or proprietary nature that Consultant
            receives, reviews or has access to in connection with the services
            to be performed for the benefit of the Company hereunder or which
            Consultant creates or has created or compiled for the Company as the
            result of the consulting services of Consultant hereunder.
            Consultant agrees not to make any copies of such confidential or
            proprietary information of the Company (except when appropriate for
            the furtherance of the business of the Company or duly and
            specifically authorized to do so) and promptly upon request, whether
            during or after the Consulting Period, to return to the Company any
            and all documentary, machine-readable or other elements or evidence
            of such confidential or proprietary information, and any copies that
            may be in Consultant's possession or control. Notwithstanding the
            foregoing, these restrictions shall not be construed to apply to (1)
            information generally available to the public; (2) information
            released by the Company generally without restriction; (3)
            information known by Consultant prior to disclosure by the Company
            or which is independently developed or acquired by Consultant
            without reliance in any way on other protected information or
            resources of the Company; or (4) information approved by the Company
            for disclosure by Consultant without restriction.

      (b)   The Consultant shall not disclose to the Company hereunder any
            information relating to products, product developments or processes
            with respect to which Consultant is under any actual or implied duty
            to any third party to keep secret, and nothing in this Agreement
            shall impose an obligation on Consultant to act contrary to any such
            actual or implied duty to others. Except as set forth below, the
            Company shall be free to use all information that Consultant conveys
            to it hereunder without any further obligation to Consultant.

      (c)   Any invention, discovery, improvement, process, formula or method
            relating to or useful in connection with the Field (collectively
            termed "Technical Information") which is made or discovered or which
            comes to the attention of Consultant during the course of
            Consultant's work for the Company hereunder will be forthwith fully
            disclosed by Consultant to the President of the Company and
            Consultant shall promptly assign to the Company his/her entire
            right, title and interest in and to such Technical Information. At
            any time during or after the Consulting Period, Consultant agrees
            that he will fully cooperate with the Company, its attorneys and
            agents, in the preparation and filing of all papers and other
            documents as may be


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Consulting Agreement

            required to perfect the Company's rights in and to any of such
            Technical Information, including, but not limited to, joining in any
            proceeding to obtain letters patent, copyrights, trademarks or other
            legal rights of the United States and of any and all other countries
            on such Inventions, provided that the Company will bear the expense
            of such proceedings. Consultant hereby designates the Company as its
            agent for, and grants to the Company a power of attorney with full
            power of substitution, which power of attorney shall be deemed
            coupled with an interest, for the purpose of effecting the foregoing
            assignments from Consultant to the Company.

      (d)   Technical Information, or other information developed directly or
            indirectly in connection with services rendered by Consultant
            pursuant to this Agreement, may be worthy of written or oral
            publication in scholarly journals or at meetings at the sole
            discretion of the Company. It is intended that such publications
            meet the highest standards of scientific excellence and integrity,
            and subject to the terms of confidentiality herein, and that
            authorship be determined in accordance with the respective
            scientific contributions of the Consultant and employees of the
            Company. Any proposed Publication covering the Technical Information
            or other information developed directly or indirectly in connection
            with services rendered by Consultant hereunder, must be approved by
            the Company in writing in advance of its submission. In no event
            will any such publication or presentation by Consultant contain any
            Proprietary Information.

5.    Records

      Upon termination of Consultant's relationship with the Company, Consultant
      shall deliver to the Company any property of the Company which may be in
      his possession including computers, software, materials, memoranda, notes,
      records, reports, notebooks, or other documents or photocopies of the
      same.

6.    Notices.

      All notices required or permitted under this Agreement shall be in writing
      and shall be deemed effective upon personal delivery, receipt of telefax,
      delivery by recognized courier service or upon deposit in the United
      States Mail, by registered or certified mail, postage prepaid, addressed
      to the other party at the address shown above, or at such other address or
      addresses as either party shall designate to the other in accordance with
      this Section 7.

7.    Status.

      (a)   The Consultant is retained by the Company only for the purposes and
            to the extent set forth in this Agreement. In performing services
            for the Company hereunder, Consultant is acting as an independent
            contractor and not as an employee of the Company. Consultant will
            not be entitled to receive any of the benefits provided by the
            Company to its employees and Consultant will be solely responsible
            for the payment of all federal, state and local taxes and
            contributions imposed or required on income, unemployment insurance,
            social security and any other law or regulation.


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Consulting Agreement

      (b)   The Consultant represents that neither his execution of, nor
            performance of his obligations under, this Agreement will result in
            a violation, breach or default under any term or provision of any
            contract or agreement to which Consultant is a party or by which
            he/she is bound or constitute an event which with notice, lapse or
            time, or both, would result in any such violation, breach or
            default.

8.    Indemnification.

      Consultant agrees to indemnify and hold harmless the Company and its
      directors, officers, employees, agents and other advisors from and against
      any and all actions, suits, proceedings, claims, demands, losses and
      expenses, including attorneys' fees, arising out of or relating to any (i)
      unauthorized act or statement made by Consultant in connection with the
      consulting services to be performed hereby, or (ii) violation of any
      warranty set forth in Section 8.

9.    Remedies.

      In the event of any breach by Consultant of any of the provisions of this
      Agreement, the Company shall be entitled, in addition to monetary damages
      and to any other remedies available to the Company under this Agreement
      and at law, to seek specific performance and other equitable relief,
      including injunctive relief, and to payment by Consultant of all costs and
      expenses, including attorneys' fees, incurred by the Company in
      enforcement against Consultant of the provisions of this Agreement.

10.   General Provisions.

      (a)   This Agreement shall be governed by, and construed in accordance
            with, the law of the Commonwealth of Massachusetts, without
            application of the conflicts of law provisions thereof;

      (b)   this Agreement constitutes the entire agreement and understanding of
            the parties hereto with respect to the subject matter hereof and
            supersedes and terminates all prior agreements and undertakings,
            both written and oral;

      (c)   the rights and obligations of Consultant pursuant to this Agreement
            shall not be assignable by Consultant;

      (d)   this Agreement shall be binding upon and inure solely to the benefit
            of the respective successors and assigns of the parties hereto;

      (e)   this Agreement may not be amended or modified except by an
            instrument in writing signed by the parties hereto; and

      (f)   this Agreement may be executed in one or more counterparts, and by
            the different parties hereto in separate counterparts, each of which
            when executed shall be deemed to be an original but all of which
            taken together shall constitute one and the same agreement.


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Consulting Agreement

IN WITNESS WHEREOF, the parties hereto have executed this Agreement under seal
as of the day first written above.

                                VARIAGENICS, INC.


                                By: /s/ Richard P. Shea
                                    -------------------------------------------
                                    Richard P. Shea, Chief Financial Officer


                                By: /s/ Alan Cromarty Houston
                                    -------------------------------------------
                                    Alan Cromarty Houston


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Consulting Agreement

                                VARIAGENICS, INC.
                        CONSULTING AGREEMENT - EXHIBIT A

1.    Services to be provided by Consultant.

Consultant shall provide services in Clinical Development and Medical Affairs as
requested by Variagenics. Consultant will work 40 hours per week for
Variagenics, and shall make reasonable efforts to be present at Variagenics'
facilities when necessary. Consulting services shall be approved by Taylor
Crouch, CEO, or Richard P. Shea, Chief Financial Officer, and from time to time,
reports shall be prepared by the Consultant summarizing the work performed and
planned.

2.    Compensation to Consultant.

Consultant shall be paid $4,038.47 per week for each week worked. In addition,
subject to the approval by the Company's Board of Directors, Consultant shall be
granted stock options for the purchase of 100,000 shares of common stock of the
Company at an exercise price determined in good faith by the Board to be fair
market value. Your right to exercise these options will vest 12/48 of the amount
twelve (12) months from the date of this agreement and 1/48 of the amount
vesting monthly thereafter for thirty-six (36) months. The vesting cycle will
end upon termination of the agreement but will continue if the Consultant
becomes an Employee of the Company.


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