Document:

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                                                                   EXHIBIT 10.22

                                                         FOR GRANTS TO DIRECTORS
                                       [APPROVED BY THE BOARD OF DIRECTORS 1/05]

                      NON-QUALIFIED STOCK OPTION AGREEMENT

                                 ARCHEMIX CORP.

     AGREEMENT made as of the ___ day of _______ 200_, between Archemix Corp.
(the "Company"), a Delaware corporation having a principal place of business in
Cambridge, Massachusetts, and _______________ of ___________ (the
"Participant").

     WHEREAS, the Company desires to grant to the Participant an Option to
purchase shares of its common stock, $.001 par value per share (the "Shares"),
under and for the purposes set forth in the Company's 2001 Employee, Director
and Consultant Stock Plan (the "Plan");

     WHEREAS, the Company and the Participant understand and agree that any
terms used and not defined herein have the same meanings as in the Plan; and

     WHEREAS, the Company and the Participant each intend that the Option
granted herein shall be a Non-Qualified Option.

     NOW, THEREFORE, in consideration of the mutual covenants hereinafter set
forth and for other good and valuable consideration, the parties hereto agree as
follows:

     1. GRANT OF OPTION.

     The Company hereby grants to the Participant the right and option to
purchase all or any part of an aggregate of _______________ Shares, on the terms
and conditions and subject to all the limitations set forth herein, under United
States securities and tax laws, and in the Plan, which is incorporated herein by
reference. The Participant acknowledges receipt of a copy of the Plan.

     2. PURCHASE PRICE.

     The purchase price of the Shares covered by the Option shall be $_____ per
Share, subject to adjustment, as provided in the Plan, in the event of a stock
split, reverse stock split or other events affecting the holders of Shares after
the date hereof (the "Purchase Price"). Payment shall be made in accordance with
Paragraph 8 of the Plan.

     3. EXERCISABILITY OF OPTION.

     Subject to the terms and conditions set forth in this Agreement and the
Plan, the Option granted hereby shall become exercisable as follows:

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<TABLE>
<S>                                            <C>
On the first anniversary of the date of this   up to _________ Shares
   Agreement

Every three months thereafter until the        an additional _________ Shares
   fourth anniversary of this Agreement.
</TABLE>

     Alternatively, at the election of the Participant, the Option may be
exercised in whole or in part at any time as to Shares which have not yet vested
in accordance with the above schedule; provided however, as a condition to
exercising the Option for such unvested Shares, the Participant shall execute a
Restricted Stock Agreement in the form attached hereto as Exhibit C.

     The foregoing rights are cumulative and are subject to the other terms and
conditions of this Agreement and the Plan.

     4. TERM OF OPTION.

     The Option shall terminate ten years from the date of this Agreement, but
shall be subject to earlier termination as provided herein or in the Plan.

     If the Participant ceases to be a director of the Company or of an
Affiliate (for any reason other than the death or Disability of the Participant
or termination of the Participant for "cause" as defined in the Plan), the
Option may be exercised, if it has not previously terminated, within three years
after the date the Participant ceases to be a director of the Company or an
Affiliate, or within the originally prescribed term of the Option, whichever is
earlier, but may not be exercised thereafter. In such event, the Option shall be
exercisable only as to Shares which have vested as of the date of termination of
service in accordance with the schedule set forth in Section 3 above and not as
to unvested Shares and only to the extent that the Option is in effect at the
date of such cessation of directorship.

     In the event the Participant's directorship is terminated by the Company or
an Affiliate for "cause" as defined in the Plan, the Participant's right to
exercise any unexercised portion of this Option shall cease immediately as of
the time the Participant is notified his or her directorship is terminated for
"cause", and this Option shall thereupon terminate. Notwithstanding anything
herein to the contrary, if subsequent to the Participant's termination, but
prior to the exercise of the Option, the Board of Directors of the Company
determines that, either prior or subsequent to the Participant's termination,
the Participant engaged in conduct which would constitute "cause," then the
Participant shall immediately cease to have any right to exercise the Option and
this Option shall thereupon terminate.

     In the event of the Disability of the Participant, as determined in
accordance with the Plan, the Option shall be exercisable within three years
after the Participant's termination of service or, if earlier, within the term
originally prescribed by the Option. In such event, the Option shall be
exercisable:

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     (a)  to the extent that the Option has become exercisable but has not been
          exercised as of the date of Disability; and

     (b)  in the event rights to exercise the Option accrue periodically, to the
          extent of a pro rata portion through the date of Disability of any
          additional vesting rights that would have accrued on the next vesting
          date had the Participant not become Disabled. The proration shall be
          based upon the number of days accrued in the current vesting period
          prior to the date of Disability.

     In the event of the death of the Participant while a director of the
Company or of an Affiliate, the Option shall be exercisable by the Participant's
Survivors within three years after the date of death of the Participant or, if
earlier, within the originally prescribed term of the Option. In such event, the
Option shall be exercisable:

     (x)  to the extent that the Option has become exercisable but has not been
          exercised as of the date of death; and

     (y) in the event rights to exercise the Option accrue periodically, to the
          extent of a pro rata portion through the date of death of any
          additional vesting rights that would have accrued on the next vesting
          date had the Participant not died. The proration shall be based upon
          the number of days accrued in the current vesting period prior to the
          Participant's date of death.

     5. METHOD OF EXERCISING OPTION.

     Subject to the terms and conditions of this Agreement, the Option may be
exercised by written notice to the Company or its designee, in substantially the
form of Exhibit A attached hereto. Such notice shall state the number of Shares
with respect to which the Option is being exercised and shall be signed by the
person exercising the Option. Payment of the Purchase Price for such Shares
shall be made in accordance with Paragraph 8 of the Plan. The Company shall
deliver a certificate or certificates representing such Shares as soon as
practicable after the notice shall be received, provided, however, that the
Company may delay issuance of such Shares until completion of any action or
obtaining of any consent, which the Company deems necessary under any applicable
law (including, without limitation, state securities or "blue sky" laws). The
certificate or certificates for the Shares as to which the Option shall have
been so exercised shall be registered in the Company's share register in the
name of the person so exercising the Option (or, if the Option shall be
exercised by the Participant and if the Participant shall so request in the
notice exercising the Option, shall be registered in the name of the Participant
and another person jointly, with right of survivorship) and shall be delivered
as provided above to or upon the written order of the person exercising the
Option. In the event the Option shall be exercised, pursuant to Section 4
hereof, by any person other than the Participant, such notice shall be
accompanied by appropriate proof of the right of such person to exercise the
Option. All Shares that shall be purchased upon the exercise of the Option as
provided herein shall be fully paid and nonassessable.

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     6. PARTIAL EXERCISE.

     Exercise of this Option to the extent above stated may be made in part at
any time and from time to time within the above limits, except that no
fractional share shall be issued pursuant to this Option.

     7. NON-ASSIGNABILITY.

     The Option shall not be transferable by the Participant otherwise than by
will or by the laws of descent and distribution or pursuant to a qualified
domestic relations order as defined by the Code or Title I of the Employee
Retirement Income Security Act or the rules thereunder. However, the
Participant, with the approval of the Administrator, may transfer the Option for
no consideration to or for the benefit of the Participant's Immediate Family
(including, without limitation, to a trust for the benefit of the Participant's
Immediate Family or to a partnership or limited liability company for one or
more members of the Participant's Immediate Family), subject to such limits as
the Administrator may establish, and the transferee shall remain subject to all
the terms and conditions applicable to the Option prior to such transfer and
each such transferee shall so acknowledge in writing as a condition precedent to
the effectiveness of such transfer. The term "Immediate Family" shall mean the
Participant's spouse, former spouse, parents, children, stepchildren, adoptive
relationships, sisters, brothers, nieces, nephews and grandchildren (and, for
this purpose, shall also include the Participant.) Except as provided in the
previous sentence, the Option shall be exercisable, during the Participant's
lifetime, only by the Participant (or, in the event of legal incapacity or
incompetency, by the Participant's guardian or representative) and shall not be
assigned, pledged or hypothecated in any way (whether by operation of law or
otherwise) and shall not be subject to execution, attachment or similar process.
Any attempted transfer, assignment, pledge, hypothecation or other disposition
of the Option or of any rights granted hereunder contrary to the provisions of
this Section 7, or the levy of any attachment or similar process upon the Option
shall be null and void.

     8. NO RIGHTS AS STOCKHOLDER UNTIL EXERCISE.

     The Participant shall have no rights as a stockholder with respect to
Shares subject to this Agreement until registration of the Shares in the
Company's share register in the name of the Participant. Except as is expressly
provided in the Plan with respect to certain changes in the capitalization of
the Company, no adjustment shall be made for dividends or similar rights for
which the record date is prior to the date of such registration.

     9. ADJUSTMENTS.

     The Plan contains provisions covering the treatment of Options in a number
of contingencies such as stock splits and mergers. Provisions in the Plan for
adjustment with respect to stock subject to Options and the related provisions
with respect to successors to the business of the Company are hereby made
applicable hereunder and are incorporated herein by reference.

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     10. TAXES.

     The Participant acknowledges that upon exercise of the Option the
Participant will be deemed to have taxable income measured by the difference
between the then fair market value of the Shares received upon exercise and the
price paid for such Shares pursuant to this Agreement. The Participant
acknowledges that any income or other taxes due from him or her with respect to
this Option or the Shares issuable pursuant to this Option shall be the
Participant's responsibility.

     The Participant agrees that the Company may withhold from the Participant's
remuneration, if any, the minimum statutory amount of federal, state and local
withholding taxes attributable to such amount that is considered compensation
includable in such person's gross income. At the Company's discretion, the
amount required to be withheld may be withheld in cash from such remuneration,
or in kind from the Shares otherwise deliverable to the Participant on exercise
of the Option. The Participant further agrees that, if the Company does not
withhold an amount from the Participant's remuneration sufficient to satisfy the
Company's income tax withholding obligation, the Participant will reimburse the
Company on demand, in cash, for the amount under-withheld.

     11. PURCHASE FOR INVESTMENT.

     Unless the offering and sale of the Shares to be issued upon the particular
exercise of the Option shall have been effectively registered under the
Securities Act of 1933, as now in force or hereafter amended (the "1933 Act"),
the Company shall be under no obligation to issue the Shares covered by such
exercise unless and until the following conditions have been fulfilled:

     (a)  The person(s) who exercise the Option shall warrant to the Company, at
          the time of such exercise, that such person(s) are acquiring such
          Shares for their own respective accounts, for investment, and not with
          a view to, or for sale in connection with, the distribution of any
          such Shares, in which event the person(s) acquiring such Shares shall
          be bound by the provisions of the following legend which shall be
          endorsed upon the certificate(s) evidencing the Shares issued pursuant
          to such exercise:

               "The shares represented by this certificate have been taken for
               investment and they may not be sold or otherwise transferred by
               any person, including a pledgee, unless (1) either (a) a
               Registration Statement with respect to such shares shall be
               effective under the Securities Act of 1933, as amended, or (b)
               the Company shall have received an opinion of counsel
               satisfactory to it that an exemption from registration under such
               Act is then available, and (2) there shall have been compliance
               with all applicable state securities laws;" and

     (b)  If the Company so requires, the Company shall have received an opinion
          of its counsel that the Shares may be issued upon such particular
          exercise in compliance with the 1933 Act without registration
          thereunder. Without limiting the generality of the foregoing, the
          Company may delay issuance of the Shares until completion

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          of any action or obtaining of any consent, which the Company deems
          necessary under any applicable law (including without limitation state
          securities or "blue sky" laws).

     12. RESTRICTIONS ON TRANSFER OF SHARES.

     12.1 The Shares acquired by the Participant pursuant to the exercise of the
Option granted hereby shall not be transferred by the Participant except as
permitted herein.

     12.2 In the event of the Participant's termination of service for any
reason, the Company shall have the option, but not the obligation, to repurchase
all or any part of the Shares issued pursuant to this Agreement (including,
without limitation, Shares purchased after termination of service, Disability or
death in accordance with Section 4 hereof). In the event the Company does not,
upon the termination of service of the Participant (as described above),
exercise its option pursuant to this Section 12.2, the restrictions set forth in
the balance of this Agreement shall not thereby lapse, and the Participant for
himself or herself, his or her heirs, legatees, executors, administrators and
other successors in interest, agrees that the Shares shall remain subject to
such restrictions. The following provisions shall apply to a repurchase under
this Section 12.2:

     (i)  The per share repurchase price of the Shares to be sold to the Company
          upon exercise of its option under this Section 12.2 shall be equal to
          the Fair Market Value of each such Share determined in accordance with
          the Plan as of the date of termination of service.

     (ii) The Company's option to repurchase the Participant's Shares in the
          event of termination of service shall be valid for a period of three
          years commencing with the date of such termination of service.

     (iii) In the event the Company shall be entitled to and shall elect to
          exercise its option to repurchase the Participant's Shares under this
          Section 12.2, the Company shall notify the Participant, or in case of
          death, his or her Survivor, in writing of its intent to repurchase the
          Shares. Such written notice may be mailed by the Company up to and
          including the last day of the time period provided for in Section
          12.2(ii) for exercise of the Company's option to repurchase.

     (iv) The written notice to the Participant shall specify the address at,
          and the time and date on, which payment of the repurchase price is to
          be made (the "Closing"). The date specified shall not be less than ten
          days nor more than 60 days from the date of the mailing of the notice,
          and the Participant or his or her successor in interest with respect
          to the Shares shall have no further rights as the owner thereof from
          and after the date specified in the notice. At the Closing, the
          repurchase price shall be delivered to the Participant or his or her
          successor in interest and the Shares being purchased, duly endorsed
          for transfer, shall, to the extent that they are not then in the
          possession of the Company, be delivered to the Company by the
          Participant or his or her successor in interest.

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     12.3 It shall be a condition precedent to the validity of any sale or other
transfer of any Shares by the Participant that the following restrictions be
complied with (except as hereinafter otherwise provided):

     (i)  No Shares owned by the Participant may be sold, pledged or otherwise
          transferred (including by gift or devise) to any person or entity,
          voluntarily, or by operation of law, except in accordance with the
          terms and conditions hereinafter set forth.

     (ii) Before selling or otherwise transferring all or part of the Shares,
          the Participant shall give written notice of such intention to the
          Company, which notice shall include the name of the proposed
          transferee, the proposed purchase price per share, the terms of
          payment of such purchase price and all other matters relating to such
          sale or transfer and shall be accompanied by a copy of the binding
          written agreement of the proposed transferee to purchase the Shares of
          the Participant. Such notice shall constitute a binding offer by the
          Participant to sell to the Company such number of the Shares then held
          by the Participant as are proposed to be sold in the notice at the
          monetary price per share designated in such notice, payable on the
          terms offered to the Participant by the proposed transferee (provided,
          however, that the Company shall not be required to meet any
          non-monetary terms of the proposed transfer, including, without
          limitation, delivery of other securities in exchange for the Shares
          proposed to be sold). The Company shall give written notice to the
          Participant as to whether such offer has been accepted in whole by the
          Company within sixty days after its receipt of written notice from the
          Participant. The Company may only accept such offer in whole and may
          not accept such offer in part. Such acceptance notice shall fix a
          time, location and date for the closing on such purchase ("Closing
          Date") which shall not be less than ten nor more than sixty days after
          the giving of the acceptance notice, provided, however, if any of the
          Shares to be sold pursuant to this Section 12.3 have been held by the
          Participant for less than six months, then the Closing Date may be
          extended by the Company until no more than ten days after such Shares
          have been held by the Participant for six months. The place for such
          closing shall be at the Company's principal office. At such closing,
          the Participant shall accept payment as set forth herein and shall
          deliver to the Company in exchange therefor certificates for the
          number of Shares stated in the notice accompanied by duly executed
          instruments of transfer.

     (iii) If the Company shall fail to accept any such offer, the Participant
          shall be free to sell all, but not less than all, of the Shares set
          forth in his or her notice to the designated transferee at the price
          and terms designated in the Participant's notice, provided that (i)
          such sale is consummated within six months after the giving of notice
          by the Participant to the Company as aforesaid, and (ii) the
          transferee first agrees in writing to be bound by the provisions of
          this Section 12 so that such transferee (and all subsequent
          transferees) shall thereafter only be permitted to sell or transfer
          the Shares in accordance with the terms hereof. After the

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          expiration of such six months, the provisions of this Section 12.3
          shall again apply with respect to any proposed voluntary transfer of
          the Participant's Shares.

     (iv) The restrictions on transfer contained in this Section 12.3 shall not
          apply to (a) transfers by the Participant to his or her spouse or
          children or to a trust for the benefit of his or her spouse or
          children, (b) transfers by the Participant to his or her guardian or
          conservator, and (c) or transfers by the Participant, in the event of
          his or her death, to his or her executor(s) or administrator(s) or to
          trustee(s) under his or her will (collectively, "Permitted
          Transferees"); provided however, that in any such event the Shares so
          transferred in the hands of each such Permitted Transferee shall
          remain subject to this Agreement, and each such Permitted Transferee
          shall so acknowledge in writing as a condition precedent to the
          effectiveness of such transfer.

     (v)  The provisions of this Section 12.3 may be waived by the Company. Any
          such waiver may be unconditional or based upon such conditions as the
          Company may impose.

     12.4 In the event that the Participant or his or her successor in interest
fails to deliver the Shares to be repurchased by the Company under this
Agreement, the Company may elect (a) to establish a segregated account in the
amount of the repurchase price, such account to be turned over to the
Participant or his or her successor in interest upon delivery of such Shares,
and (b) immediately to take such action as is appropriate to transfer record
title of such Shares from the Participant to the Company and to treat the
Participant and such Shares in all respects as if delivery of such Shares had
been made as required by this Agreement. The Participant hereby irrevocably
grants the Company a power of attorney which shall be coupled with an interest
for the purpose of effectuating the preceding sentence.

     12.5 If the Company shall pay a stock dividend or declare a stock split on
or with respect to any of its Common Stock, or otherwise distribute securities
of the Company to the holders of its Common Stock, the number of shares of stock
or other securities of Company issued with respect to the shares then subject to
the restrictions contained in this Agreement shall be added to the Shares
subject to the Company's rights to repurchase pursuant to this Agreement. If the
Company shall distribute to its stockholders shares of stock of another
corporation, the shares of stock of such other corporation, distributed with
respect to the Shares then subject to the restrictions contained in this
Agreement, shall be added to the Shares subject to the Company's rights to
repurchase pursuant to this Agreement.

     12.6 If the outstanding shares of Common Stock of the Company shall be
subdivided into a greater number of shares or combined into a smaller number of
shares, or in the event of a reclassification of the outstanding shares of
Common Stock of the Company, or if the Company shall be a party to a merger,
consolidation or capital reorganization, there shall be substituted for the
Shares then subject to the restrictions contained in this Agreement such amount
and kind of securities as are issued in such subdivision, combination,
reclassification, merger, consolidation or capital reorganization in respect of
the Shares subject immediately prior thereto to the Company's rights to
repurchase pursuant to this Agreement.

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     12.7 The Company shall not be required to transfer any Shares on its books
which shall have been sold, assigned or otherwise transferred in violation of
this Agreement, or to treat as owner of such Shares, or to accord the right to
vote as such owner or to pay dividends to, any person or organization to which
any such Shares shall have been so sold, assigned or otherwise transferred, in
violation of this Agreement.

     12.8 The provisions of Sections 12.1, 12.2 and 12.3 shall terminate upon
the consummation of a public offering of any of the Company's securities
pursuant to a registration statement filed with the Securities and Exchange
Commission.

     12.9 The Participant agrees that in the event that the Company effects an
initial public offering of the Common Stock of the Company registered under the
Securities Act, the Shares may not be sold, offered for sale or otherwise
disposed of, directly or indirectly, without the prior written consent of the
managing underwriter(s) of the offering, for such period of time after the
execution of an underwriting agreement in connection with the such offering that
all of the Company's then directors and executive officers agree to be similarly
bound.

     12.10 The Participant acknowledges and agrees that neither the Company, its
shareholders nor its directors and officers, has any duty or obligation to
disclose to the Participant any material information regarding the business of
the Company or affecting the value of the Shares before, at the time of, or
following a termination of service of the Participant by the Company, including,
without limitation, any information concerning plans for the Company to make a
public offering of its securities or to be acquired by or merged with or into
another firm or entity.

     12.11 All certificates representing the Shares to be issued to the
Participant pursuant to this Agreement shall have endorsed thereon a legend
substantially as follows: "The shares represented by this certificate are
subject to restrictions set forth in a Non-Qualified Stock Option Agreement
dated ________, 200__ with this Company, a copy of which Agreement is available
for inspection at the offices of the Company or will be made available upon
request."

     13. NO OBLIGATION TO MAINTAIN RELATIONSHIP.

     The Company is not by the Plan or this Option obligated to continue the
Participant as a director of the Company or an Affiliate. The Participant
acknowledges: (i) that the Plan is discretionary in nature and may be suspended
or terminated by the Company at any time; (ii) that the grant of the Option is a
one-time benefit which does not create any contractual or other right to receive
future grants of options, or benefits in lieu of options; (iii) that all
determinations with respect to any such future grants, including, but not
limited to, the times when options shall be granted, the number of shares
subject to each option, the option price, and the time or times when each option
shall be exercisable, will be at the sole discretion of the Company; (iv) that
the Participant's participation in the Plan is voluntary; (v) that the value of
the Option is an extraordinary item of compensation which is outside the scope
of the Participant's employment contract, if any; and (vi) that the Option is
not part of normal or expected compensation for

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purposes of calculating any severance, resignation, redundancy, end of service
payments, bonuses, long-service awards, pension or retirement benefits or
similar payments.

     14. NOTICES.

     Any notices required or permitted by the terms of this Agreement or the
Plan shall be given by recognized courier service, facsimile, registered or
certified mail, return receipt requested, addressed as follows:

If to the Company:

                       Archemix Corp.
                       300 Third Street
                       Cambridge, MA 02142
                       Attn: President

If to the Participant:

                       ______________________________
                       ______________________________
                       ______________________________

or to such other address or addresses of which notice in the same manner has
previously been given. Any such notice shall be deemed to have been given upon
the earlier of receipt, one business day following delivery to a recognized
courier service or three business days following mailing by registered or
certified mail.

     15. GOVERNING LAW; CONSENT TO JURISDICTION.

     This Agreement shall be construed and enforced in accordance with the law
of the State of Delaware, without giving effect to the conflict of law
principles thereof. For the purpose of litigating any dispute that arises under
this Agreement, the parties hereby consent to exclusive jurisdiction in the
Commonwealth of Massachusetts and agree that such litigation shall be conducted
in the courts of Middlesex County, Massachusetts or the federal courts of the
United States for the District of Massachusetts.

     16. BENEFIT OF AGREEMENT.

     Subject to the provisions of the Plan and the other provisions hereof, this
Agreement shall be for the benefit of and shall be binding upon the heirs,
executors, administrators, successors and assigns of the parties hereto.

     17. ENTIRE AGREEMENT.

     This Agreement, together with the Plan, embodies the entire agreement and
understanding between the parties hereto with respect to the subject matter
hereof and supersedes all prior oral or written agreements and understandings
relating to the subject matter hereof. No statement, representation, warranty,
covenant or agreement not expressly set forth in this

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Agreement shall affect or be used to interpret, change or restrict, the express
terms and provisions of this Agreement, provided, however, in any event, this
Agreement shall be subject to and governed by the Plan.

     18. MODIFICATIONS AND AMENDMENTS.

     The terms and provisions of this Agreement may be modified or amended as
provided in the Plan.

     19. WAIVERS AND CONSENTS.

     Except as provided in the Plan, the terms and provisions of this Agreement
may be waived, or consent for the departure therefrom granted, only by written
document executed by the party entitled to the benefits of such terms or
provisions. No such waiver or consent shall be deemed to be or shall constitute
a waiver or consent with respect to any other terms or provisions of this
Agreement, whether or not similar. Each such waiver or consent shall be
effective only in the specific instance and for the purpose for which it was
given, and shall not constitute a continuing waiver or consent.

     20. DATA PRIVACY.

     By entering into this Agreement, the Participant: (i) authorizes the
Company and each Affiliate, and any agent of the Company or any Affiliate
administering the Plan or providing Plan recordkeeping services, to disclose to
the Company or any of its Affiliates such information and data as the Company or
any such Affiliate shall request in order to facilitate the grant of options and
the administration of the Plan; (ii) waives any data privacy rights he or she
may have with respect to such information; and (iii) authorizes the Company and
each Affiliate to store and transmit such information in electronic form.

     21. CONSENT OF SPOUSE.

     If the Participant is married as of the date of this Agreement, the
Participant's spouse shall execute a Consent of Spouse in the form of Exhibit B
hereto, effective as of the date hereof. Such consent shall not be deemed to
confer or convey to the spouse any rights in the Shares that do not otherwise
exist by operation of law or the agreement of the parties. If the Participant
marries or remarries subsequent to the date hereof, the Participant shall, not
later than 60 days thereafter, obtain his or her new spouse's acknowledgement of
and consent to the existence and binding effect of Section 12.2 of this
Agreement by such spouse's executing and delivering a Consent of Spouse in the
form of Exhibit B.

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     IN WITNESS WHEREOF, the Company has caused this Agreement to be executed by
its duly authorized officer, and the Participant has hereunto set his or her
hand, all as of the day and year first above written.

                                        ARCHEMIX CORP.

                                        By:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------

                                        ----------------------------------------
                                        Participant

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                                                                       Exhibit A

                NOTICE OF EXERCISE OF NON-QUALIFIED STOCK OPTION

                         [FORM FOR UNREGISTERED SHARES]

To: Archemix Corp.

Ladies and Gentlemen:

     I hereby exercise my Non-Qualified Stock Option to purchase __________
shares (the "Shares") of the common stock, $.001 par value, of Archemix Corp.
(the "Company"), at the exercise price of $_____ per share, pursuant to and
subject to the terms of that certain Non-Qualified Stock Option Agreement
between the undersigned and the Company dated ________, 200_.

     I am aware that the Shares have not been registered under the Securities
Act of 1933, as amended (the "1933 Act"), or any state securities laws. I
understand that the reliance by the Company on exemptions under the 1933 Act is
predicated in part upon the truth and accuracy of the statements by me in this
Notice of Exercise.

     I hereby represent and warrant that (1) I have been furnished with all
information which I deem necessary to evaluate the merits and risks of the
purchase of the Shares; (2) I have had the opportunity to ask questions
concerning the Shares and the Company and all questions posed have been answered
to my satisfaction; (3) I have been given the opportunity to obtain any
additional information I deem necessary to verify the accuracy of any
information obtained concerning the Shares and the Company; and (4) I have such
knowledge and experience in financial and business matters that I am able to
evaluate the merits and risks of purchasing the Shares and to make an informed
investment decision relating thereto.

     I hereby represent and warrant that I am purchasing the Shares for my own
personal account for investment and not with a view to the sale or distribution
of all or any part of the Shares.

     I understand that because the Shares have not been registered under the
1933 Act, I must continue to bear the economic risk of the investment for an
indefinite time and the Shares cannot be sold unless the Shares are subsequently
registered under applicable federal and state securities laws or an exemption
from such registration requirements is available.

     I agree that I will in no event sell or distribute or otherwise dispose of
all or any part of the Shares unless (1) there is an effective registration
statement under the 1933 Act and applicable state securities laws covering any
such transaction involving the Shares or (2) the Company receives an opinion of
my legal counsel (concurred in by legal counsel for the

                                       A-1

<PAGE>

Company) stating that such transaction is exempt from registration or the
Company otherwise satisfies itself that such transaction is exempt from
registration.

     I consent to the placing of a legend on my certificate for the Shares
stating that the Shares have not been registered and setting forth the
restriction on transfer contemplated hereby and to the placing of a stop
transfer order on the books of the Company and with any transfer agents against
the Shares until the Shares may be legally resold or distributed without
restriction.

     I understand that at the present time Rule 144 of the Securities and
Exchange Commission (the "SEC") may not be relied on for the resale or
distribution of the Shares by me. I understand that the Company has no
obligation to me to register the sale of the Shares with the SEC and has not
represented to me that it will register the sale of the Shares.

     I understand the terms and restrictions on the right to dispose of the
Shares set forth in the 2001 Employee, Director and Consultant Stock Plan and
the Non-Qualified Stock Option Agreement, both of which I have carefully
reviewed. I consent to the placing of a legend on my certificate for the Shares
referring to such restriction and the placing of stop transfer orders until the
Shares may be transferred in accordance with the terms of such restrictions.

     I have considered the Federal, state and local income tax implications of
the exercise of my Option and the purchase and subsequent sale of the Shares.

     I am paying the option exercise price for the Shares as follows:

                    ________________________________________

     Please issue the stock certificate for the Shares (check one):

     [ ] to me; or

     [ ] to me and ________________, as joint tenants with right of survivorship

and mail the certificate to me at the following address:

________________________________________

________________________________________

________________________________________

          My mailing address for shareholder communications, if different from
the address listed above is:

                                       A-2

<PAGE>

________________________________________

________________________________________

________________________________________

                                        Very truly yours,

                                        ----------------------------------------
                                        Participant (signature)

                                        ----------------------------------------
                                        Print Name

                                        ----------------------------------------
                                        Date

                                        ----------------------------------------
                                        Social Security Number

                                       A-3

<PAGE>

                                                                       Exhibit A

                NOTICE OF EXERCISE OF NON-QUALIFIED STOCK OPTION

                          [FORM FOR REGISTERED SHARES]

TO: Archemix Corp.

IMPORTANT NOTICE: This form of Notice of Exercise may only be used at such time
as the Company has filed a Registration Statement with the Securities and
Exchange Commission under which the issuance of the Shares for which this
exercise is being made is registered and such Registration Statement remains
effective.

Ladies and Gentlemen:

     I hereby exercise my Non-Qualified Stock Option to purchase _________
shares (the "Shares") of the common stock, $.001 par value, of Archemix Corp.
(the "Company"), at the exercise price of $________ per share, pursuant to and
subject to the terms of that certain Non-Qualified Stock Option Agreement
between the undersigned and the Company dated _______________, 200_.

     I understand the nature of the investment I am making and the financial
risks thereof. I am aware that it is my responsibility to have consulted with
competent tax and legal advisors about the relevant national, state and local
income tax and securities laws affecting the exercise of the Option and the
purchase and subsequent sale of the Shares.

     I am paying the option exercise price for the Shares as follows:

                    ________________________________________

     Please issue the Shares (check one):

     [ ] to me; or

     [ ] to me and ____________________________, as joint tenants with right of
survivorship,

     at the following address:

     ________________________________________

     ________________________________________

     ________________________________________

                                       A-1

<PAGE>

          My mailing address for shareholder communications, if different from
the address listed above, is:

     ________________________________________

     ________________________________________

     ________________________________________

                                        Very truly yours,

                                        ----------------------------------------
                                        Participant (signature)

                                        ----------------------------------------
                                        Print Name

                                        ----------------------------------------
                                        Date

                                        ----------------------------------------
                                        Social Security Number

                                       A-2

<PAGE>

                                                                       Exhibit B

                                CONSENT OF SPOUSE

     I, ____________________________, spouse of _____________________________,
acknowledge that I have read the Non-Qualified Stock Option Agreement dated as
of _______________, 200__ (the "Agreement") to which this Consent is attached as
Exhibit B and that I know its contents. Capitalized terms used and not defined
herein shall have the meanings assigned to such terms in the Agreement. I am
aware that by its provisions the Shares granted to my spouse pursuant to the
Agreement are subject to a right of repurchase in favor of Archemix Corp. (the
"Company") and that, accordingly, the Company has the right to repurchase up to
all of the Shares of which I may become possessed as a result of a gift from my
spouse or a court decree and/or any property settlement in any domestic
litigation.

     I hereby agree that my interest, if any, in the Shares subject to the
Agreement shall be irrevocably bound by the Agreement and further understand and
agree that any community property interest I may have in the Shares shall be
similarly bound by the Agreement.

     I agree to the repurchase right described in Section 12.2 of the Agreement
and I hereby consent to the repurchase of the Shares by the Company and the sale
of the Shares by my spouse or my spouse's legal representative in accordance
with the provisions of the Agreement. Further, as part of the consideration for
the Agreement, I agree that at my death, if I have not disposed of any interest
of mine in the Shares by an outright bequest of the Shares to my spouse, then
the Company shall have the same rights against my legal representative to
exercise its rights of repurchase with respect to any interest of mine in the
Shares as it would have had pursuant to the Agreement if I had acquired the
Shares pursuant to a court decree in domestic litigation.

     I AM AWARE THAT THE LEGAL, FINANCIAL AND RELATED MATTERS CONTAINED IN THE
AGREEMENT ARE COMPLEX AND THAT I AM FREE TO SEEK INDEPENDENT PROFESSIONAL
GUIDANCE OR COUNSEL WITH RESPECT TO THIS CONSENT. I HAVE EITHER SOUGHT SUCH
GUIDANCE OR COUNSEL OR DETERMINED AFTER REVIEWING THE AGREEMENT CAREFULLY THAT I
WILL WAIVE SUCH RIGHT.

     Dated as of the _______ day of ________________, 200__.

                                        ________________________________________
                                        Print name:

                                       B-1

<PAGE>

                                                                       EXHIBIT C

                           RESTRICTED STOCK AGREEMENT

                                 ARCHEMIX CORP.

     AGREEMENT made as of the ___ day of ____________, 200__ (the "Grant Date"),
between Archemix Corp. (the "Company"), a Delaware corporation having its
principal place of business in Cambridge, Massachusetts, and ________________ of
________________________, (the "Participant").

     WHEREAS, the Company has adopted the Archemix Corp. 2001 Employee, Director
and Consultant Stock Plan (the "Plan") to promote the interests of the Company
by providing an incentive for employees, directors and consultants of the
Company or its Affiliates;

     WHEREAS, the parties hereto understand and agree that any terms used and
not defined herein have the meanings ascribed to such terms in the Plan;

     WHEREAS, pursuant to the exercise of an option granted to the Participant
pursuant to a Non-Qualified Stock Option Agreement dated ___________ by and
between the Company and the Participant issued under the Plan (the "Option
Agreement"), which Option Agreement and Plan are hereby incorporated herein by
reference, the Participant has elected to purchase _________ shares of the
Company's common stock, $.001 par value per share ("Common Stock"), which have
not become vested under the vesting schedule set forth in the Option Agreement
(the "Unvested Shares"). The Unvested Shares and the Shares subject to the
Option Agreement that have become vested are sometimes collectively referred to
herein as the "Shares."

     WHEREAS, as required by the Option Agreement, as a condition to the
Participant's election to exercise the option, the Participant must execute this
Agreement, which sets forth the rights and obligations of the parties with
respect to the Unvested Shares acquired upon exercise of the option pursuant to
the Option Agreement; and

     WHEREAS, Participant wishes to accept said offer in accordance with the
provisions of the Plan, all on the terms and conditions hereinafter set forth.

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

                                       C-1

<PAGE>

     1. Company's Lapsing Repurchase Right.

     (a) Lapsing Repurchase Right. Except as set forth in Subsection 1(b)
hereof, in the event that for any reason the Participant no longer is a director
of the Company or an Affiliate, the Company (or its designee) shall have the
option, but not the obligation, to purchase from the Participant (or the
Participant's Survivor), and, in the event the Company exercises such option,
the Participant (or the Participant's Survivor) shall be obligated to sell to
the Company (or its designee), at a price per Share equal to the Purchase Price,
all or any part of the Unvested Shares determined as of the date of such
termination of service (the "Lapsing Repurchase Right"). The Lapsing Repurchase
Right with respect to the Unvested Shares shall terminate as to such Unvested
Shares in accordance with the vesting schedule set forth in Section 3 of the
Option Agreement. The Company's Lapsing Repurchase Right shall be valid for a
period of one year commencing with the date of such termination of service.
Notwithstanding any other provision hereof, in the event the Company is
prohibited during such one year period from exercising its Lapsing Repurchase
Right by applicable law, then the time period during which such Lapsing
Repurchase Right may be exercised shall be extended until 30 days after the
Company is first not so prohibited.

     (b) Effect of Termination for Disability or upon Death. The following rules
apply if the Participant ceases to be a director of the Company by reason of
Disability or death: to the extent the Company's Lapsing Repurchase Right has
not lapsed as of the date of Disability or death, as case may be, the Company
may exercise such Lapsing Repurchase Right; provided, however, that the
Company's Lapsing Repurchase Right shall be deemed to have lapsed to the extent
of a pro rata portion of the Unvested Shares through the date of Disability or
death, as would have lapsed had the Participant not become Disabled or died, as
the case may be. The proration shall be based upon the number of days accrued in
such current vesting period prior to the Participant's date of Disability or
death, as the case may be.

     (c) Closing. In the event that the Company exercises the Lapsing Repurchase
Right, the Company shall notify the Participant, or, in the case of the
Participant's death, his or her Survivor, in writing of its intent to repurchase
the Unvested Shares. Such notice may be mailed by the Company up to and
including the last day of the time period provided for above for exercise of the
Lapsing Repurchase Right. The notice shall specify the place, time and date for
payment of the repurchase price (the "Closing") and the number of Unvested
Shares with respect to which the Company is exercising the Lapsing Repurchase
Right. The Closing shall be not less than ten days nor more than 60 days from
the date of mailing of the notice, and the Participant or the Participant's
Survivor with respect to the Unvested Shares which the Company elects to
repurchase shall have no further rights as the owner thereof from and after the
date specified in the notice. At the Closing, the repurchase price shall be
delivered to the Participant or the Participant's Survivor and the Unvested
Shares being repurchased, duly endorsed for transfer, shall, to the extent that
they are not then in the possession of the Company, be delivered to the Company
by the Participant or the Participant's Survivor.

     (d) Escrow. The certificates representing all Unvested Shares acquired by
the Participant hereunder which from time to time are subject to the Lapsing
Repurchase Right shall be delivered to the Company and the Company shall hold
such Unvested Shares in escrow as

                                       C-2

<PAGE>

provided in this Subsection 1(d). Promptly following receipt by the Company of a
written request from the Participant, the Company shall release from escrow and
deliver to the Participant a certificate for the whole number of Unvested
Shares, if any, as to which the Company's Lapsing Repurchase Right has lapsed.
In the event of a repurchase by the Company of Unvested Shares subject to the
Lapsing Repurchase Right, the Company shall release from escrow and cancel a
certificate for the number of Unvested Shares so repurchased. Any securities
distributed in respect of the Unvested Shares held in escrow, including, without
limitation, shares issued as a result of stock splits, stock dividends or other
recapitalizations, shall also be held in escrow in the same manner as the
Unvested Shares.

     (e) Prohibition on Transfer. The Participant recognizes and agrees that all
Unvested Shares which are subject to the Lapsing Repurchase Right may not be
sold, transferred, assigned, hypothecated, pledged, encumbered or otherwise
disposed of, whether voluntarily or by operation of law, other than to the
Company (or its designee). However, the Participant, with the approval of the
Administrator, may transfer the Unvested Shares for no consideration to or for
the benefit of the Participant's Immediate Family (including, without
limitation, to a trust for the benefit of the Participant's Immediate Family or
to a partnership or limited liability company for one or more members of the
Participant's Immediate Family), subject to such limits as the Administrator may
establish, and the transferee shall remain subject to all the terms and
conditions applicable to this Agreement prior to such transfer and each such
transferee shall so acknowledge in writing as a condition precedent to the
effectiveness of such transfer. The term "Immediate Family" shall mean the
Participant's spouse, former spouse, parents, children, stepchildren, adoptive
relationships, sisters, brothers, nieces and nephews and grandchildren (and, for
this purpose, shall also include the Participant. The Company shall not be
required to transfer any Unvested Shares on its books which shall have been
sold, assigned or otherwise transferred in violation of this Subsection 1(e), or
to treat as the owner of such Unvested Shares, or to accord the right to vote as
such owner or to pay dividends to, any person or organization to which any such
Unvested Shares shall have been so sold, assigned or otherwise transferred, in
violation of this Subsection 1(e). The Participant further recognizes and agrees
that all Shares remain subject to Section 12 of the Option Agreement, except
that with respect to the Unvested Shares subject to the Lapsing Repurchase
Right, this Agreement will supercede Section 12.3 of the Option Agreement.

     (f) Failure to Deliver Unvested Shares to be Repurchased. In the event that
the Unvested Shares to be repurchased by the Company under this Agreement are
not in the Company's possession pursuant to Subsection 1(d) above or otherwise
and the Participant or the Participant's Survivor fails to deliver such Unvested
Shares to the Company (or its designee), the Company may elect (i) to establish
a segregated account in the amount of the repurchase price, such account to be
turned over to the Participant or the Participant's Survivor upon delivery of
such Unvested Shares, and (ii) immediately to take such action as is appropriate
to transfer record title of such Unvested Shares from the Participant to the
Company (or its designee) and to treat the Participant and such Unvested Shares
in all respects as if delivery of such Unvested Shares had been made as required
by this Agreement. The Participant hereby irrevocably grants the Company a power
of attorney which shall be coupled with an interest for the purpose of
effectuating the preceding sentence.

                                       C-3

<PAGE>

     (g) Adjustments. The Plan contains provisions covering the treatment of
Shares in a number of contingencies such as stock splits and mergers. Provisions
in the Plan for adjustment with respect to the Shares and the related provisions
with respect to successors to the business of the Company are hereby made
applicable hereunder and are incorporated herein by reference.

     2. Legend. In addition to any legend required pursuant to the Plan or the
Option Agreement, all certificates representing the Unvested Shares to be issued
to the Participant pursuant to this Agreement shall have endorsed thereon a
legend substantially as follows:

          "The shares represented by this certificate are subject to
          restrictions set forth in a Restricted Stock Agreement dated as of
          ____________, 200__ with this Company, a copy of which Agreement is
          available for inspection at the offices of the Company or will be made
          available upon request."

     3. Purchase for Investment. If the offering and sale of the Unvested Shares
have not been effectively registered under the Securities Act of 1933, as
amended, the Participant hereby represents and warrants that he or she is
acquiring the Unvested Shares for his or her own account, for investment, and
not with a view to, or for sale in connection with, the distribution of any such
Unvested Shares.

     4. Provisions of Agreement Controlling. The Participant specifically
understands and agrees that the Unvested Shares issued under the Plan are being
sold to the Participant pursuant to the Plan and the Option Agreement, a copy of
which Plan and Option Agreement the Participant acknowledges he or she has read
and understands and by which Plan and Option Agreement he or she agrees to be
bound. The provisions of the Plan and the Option Agreement are incorporated
herein by reference. In the event of a conflict between the terms and conditions
of the Plan, this Agreement and the Option Agreement, the provisions of this
Agreement will control.

     5. Tax Liability of the Participant and Payment of Taxes. The Participant
acknowledges and agrees that any income or other taxes due from the Participant
with respect to the Unvested Shares issued pursuant to this Agreement,
including, without limitation, the Lapsing Repurchase Right, shall be the
Participant's responsibility. Without limiting the foregoing, the Participant
agrees that, to the extent that the lapsing of restrictions on disposition of
any of the Unvested Shares or the declaration of dividends on any such shares
before the lapse of such restrictions on disposition results in the
Participant's being deemed to be in receipt of earned income under the
provisions of the Code, the Company shall be entitled to immediate payment from
the Participant of the amount of any tax required to be withheld by the Company.

     Upon execution of this Agreement, the Participant may file an election
under Section 83 of the Code in substantially the form attached as Attachment I.
The Participant acknowledges that if she does not file such an election, as the
Unvested Shares are released from the Lapsing Repurchase Right in accordance
with Section 1, the Participant may have income for tax purposes equal to the
fair market value of the Unvested Shares at such date, less the price paid for
the Unvested Shares by the Participant.

                                       C-4

<PAGE>

     6. Securities Law Compliance. The Participant specifically acknowledges and
agrees that any sales of Unvested Shares shall be made in accordance with the
requirements of the Securities Act of 1933, as amended, in a transaction as to
which the Company shall have received an opinion of counsel satisfactory to it
confirming such compliance.

     7. Equitable Relief. The Participant specifically acknowledges and agrees
that in the event of a breach or threatened breach of the provisions of this
Agreement, the Option Agreement or the Plan, including the attempted transfer of
the Unvested Shares by the Participant in violation of this Agreement or the
Option Agreement, monetary damages may not be adequate to compensate the
Company, and, therefore, in the event of such a breach or threatened breach, in
addition to any right to damages, the Company shall be entitled to equitable
relief in any court having competent jurisdiction. Nothing herein shall be
construed as prohibiting the Company from pursuing any other remedies available
to it for any such breach or threatened breach.

     8. No Obligation to Maintain Relationship. The Company is not by the Plan,
the Option Agreement or this Agreement obligated to continue the Participant as
a director of the Company. The Participant acknowledges: (i) that the Plan is
discretionary in nature and may be suspended or terminated by the Company at any
time; (ii) that the grant of the Shares is a one-time benefit which does not
create any contractual or other right to receive future grants of shares, or
benefits in lieu of shares; (iii) that all determinations with respect to any
such future grants, including, but not limited to, the times when shares shall
be granted, the number of shares to be granted, the Purchase Price, and the time
or times when each share shall be free from the Lapsing Repurchase Right, will
be at the sole discretion of the Company; (iv) that the Participant's
participation in the Plan is voluntary; (v) that the value of the Shares is an
extraordinary item of compensation which is outside the scope of the
Participant's employment contract, if any; and (vi) that the Shares are not part
of normal or expected compensation for purposes of calculating any severance,
resignation, redundancy, end of service payments, bonuses, long-service awards,
pension or retirement benefits or similar payments.

     9. Notices. Any notices required or permitted by the terms of this
Agreement, the Option Agreement or the Plan shall be given by recognized courier
service, facsimile, registered or certified mail, return receipt requested,
addressed as follows:

     If to the Company:

          Archemix Corp.
          300 Third Street
          Cambridge, MA 02142
          Attn: President

     If to the Participant:

          _____________________________________

          _____________________________________

          _____________________________________

                                       C-5

<PAGE>

or to such other address or addresses of which notice in the same manner has
previously been given. Any such notice shall be deemed to have been given on the
earliest of receipt, one business day following delivery by the sender to a
recognized courier service, or three business days following mailing by
registered or certified mail.

     10. Binding Effect. This Agreement shall be for the benefit of and shall be
binding upon the parties hereto, upon their respective successors and assigns
and upon the Participant's heirs, executors, administrators.

     11. Governing Law; Consent to Jurisdiction. This Agreement shall be
construed and enforced in accordance with the law of the State of Delaware,
without giving effect to the conflict of law principles thereof. For the purpose
of litigating any dispute that arises under this Agreement, the parties hereby
consent to exclusive jurisdiction in the Commonwealth of Massachusetts and agree
that such litigation shall be conducted in the courts of Middlesex County,
Massachusetts or the federal courts of the United States for the District of
Massachusetts.

     12. Severability. If any provision of this Agreement is held to be invalid
or unenforceable by a court of competent jurisdiction, then such provision or
provisions shall be modified to the extent necessary to make such provision
valid and enforceable, and to the extent that this is impossible, then such
provision shall be deemed to be excised from this Agreement, and the validity,
legality and enforceability of the rest of this Agreement shall not be affected
thereby.

     13. Entire Agreement. This Agreement, together with the Plan and the Option
Agreement, constitutes the entire agreement and understanding between the
parties hereto with respect to the subject matter hereof and supersedes all
prior oral or written agreements and understandings relating to the subject
matter hereof. No statement, representation, warranty, covenant or agreement not
expressly set forth in this Agreement, the Option Agreement or the Plan shall
affect or be used to interpret, change or restrict the express terms and
provisions of this Agreement provided, however, in any event, this Agreement
shall be subject to and governed by the Plan.

     14. Modifications and Amendments; Waivers and Consents. The terms and
provisions of this Agreement may be modified or amended as provided in the Plan.
Except as provided in the Plan, the terms and provisions of this Agreement may
be waived, or consent for the departure therefrom granted, only by written
document executed by the party entitled to the benefits of such terms or
provisions. No such waiver or consent shall be deemed to be or shall constitute
a waiver or consent with respect to any other terms or provisions of this
Agreement, whether or not similar. Each such waiver or consent shall be
effective only in the specific instance and for the purpose for which it was
given, and shall not constitute a continuing waiver or consent.

     15. Consent of Spouse. If the Participant is married as of the date of this
Agreement, the Participant's spouse shall execute a Consent of Spouse in the
form of Attachment II hereto,

                                       C-6

<PAGE>

effective as of the date hereof. Such consent shall not be deemed to confer or
convey to the spouse any rights in the Unvested Shares that do not otherwise
exist by operation of law or the agreement of the parties. If the Participant
marries or remarries subsequent to the date hereof, the Participant shall, not
later than 60 days thereafter, obtain his or her new spouse's acknowledgement of
and consent to the existence and binding effect of all restrictions contained in
this Agreement by such spouse's executing and delivering a Consent of Spouse in
the form of Attachment II.

     16. Counterparts. This Agreement may be executed in one or more
counterparts, and by different parties hereto on separate counterparts, each of
which shall be deemed an original, but all of which together shall constitute
one and the same instrument.

     17. Data Privacy. By entering into this Agreement, the Participant: (i)
authorizes the Company and each Affiliate, and any agent of the Company or any
Affiliate administering the Plan or providing Plan record keeping services, to
disclose to the Company or any of its Affiliates such information and data as
the Company or any such Affiliate shall request in order to facilitate the grant
of Shares and the administration of the Plan; (ii) waives any data privacy
rights he or she may have with respect to such information; and (iii) authorizes
the Company and each Affiliate to store and transmit such information in
electronic form.

                      [THE NEXT PAGE IS THE SIGNATURE PAGE]

                                       C-7

<PAGE>

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

                                        ARCHEMIX CORP.

                                        By:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------

                                        PARTICIPANT:

                                        ----------------------------------------
                                        Print name:

                                       C-8

<PAGE>

                                                                    ATTACHMENT I

                    ELECTION TO INCLUDE GROSS INCOME IN YEAR
                      OF TRANSFER PURSUANT TO SECTION 83(B)
                OF THE INTERNAL REVENUE CODE OF 1986, AS AMENDED

     In accordance with Section 83(b) of the Internal Revenue Code of 1986, as
amended (the "Code"), the undersigned hereby elects to include in his gross
income as compensation for services the excess, if any, of the fair market value
of the property (described below) at the time of transfer over the amount paid
for such property.

The following sets for the information required in accordance with the Code and
the regulations promulgated hereunder:

1.   The name, address and social security number of the undersigned are:

          Name: ______________________________

          Address: ___________________________

          Social Security No.: _______________

2.   The description of the property with respect to which the election is being
     made is as follows:

     ____________ (___) shares (the "Shares") of Common Stock, $.001 par value
     per share, of Archemix Corp., a Delaware corporation (the "Company").

3.   This election is made for the calendar year ____, with respect to the
     transfer of the property to the Taxpayer on _________________.

4.   Description of restrictions: The property is subject to the following
     restrictions:

     In the event taxpayer's service to the Company or an Affiliate is
     terminated, the Company may repurchase all or any portion of the Shares
     determined as set forth below at the acquisition price paid by the
     taxpayer:

     A.   If the termination of service takes place on or prior to ____________,
          the Purchase Option will apply to all of the Shares.

     B.   If the termination of service takes place after __________, 200_, the
          number of Shares to which the Purchase Option applies shall be
          ______________ (___) Shares less ____________________ (___) Shares for
          each full twelve (12) month period elapsed after _____________, 200_
          if the taxpayer continues to provide service to the Company or an
          Affiliate.

                                       I-1

<PAGE>

5.   The fair market value at time of transfer (determined without regard to any
     restrictions other than restrictions which by their terms will never lapse)
     of the property with respect to which this election is being made was not
     more than $____ per Share.

6.   The amount paid by taxpayer for said property was $___ per Share.

7.   A copy of this statement has been furnished to the Company.

Signed this ____ day of ______, 200_.

                                        ----------------------------------------
                                        Print Name:

                                       I-2

<PAGE>

                                                                   ATTACHMENT II

                                CONSENT OF SPOUSE

     I, ____________________________, spouse of _____________________________,
acknowledge that I have read the RESTRICTED STOCK AGREEMENT dated as of
_______________, 200__ (the "Agreement") to which this Consent is attached as
Attachment II and that I know its contents. Capitalized terms used and not
defined herein shall have the meanings assigned to such terms in the Agreement.
I am aware that by its provisions the Unvested Shares granted to my spouse
pursuant to the Agreement are subject to a Lapsing Repurchase Right in favor of
Archemix Corp. (the "Company") and that, accordingly, the Company has the right
to repurchase up to all of the Unvested Shares of which I may become possessed
as a result of a gift from my spouse or a court decree and/or any property
settlement in any domestic litigation.

     I hereby agree that my interest, if any, in the Unvested Shares subject to
the Agreement shall be irrevocably bound by the Agreement and further understand
and agree that any community property interest I may have in the Unvested Shares
shall be similarly bound by the Agreement.

     I agree to the Lapsing Repurchase Right described in the Agreement and I
hereby consent to the repurchase of the Unvested Shares by the Company and the
sale of the Unvested Shares by my spouse or my spouse's legal representative in
accordance with the provisions of the Agreement. Further, as part of the
consideration for the Agreement, I agree that at my death, if I have not
disposed of any interest of mine in the Unvested Shares by an outright bequest
of the Unvested Shares to my spouse, then the Company shall have the same rights
against my legal representative to exercise its rights of repurchase with
respect to any interest of mine in the Unvested Shares as it would have had
pursuant to the Agreement if I had acquired the Unvested Shares pursuant to a
court decree in domestic litigation.

     I AM AWARE THAT THE LEGAL, FINANCIAL AND RELATED MATTERS CONTAINED IN THE
AGREEMENT ARE COMPLEX AND THAT I AM FREE TO SEEK INDEPENDENT PROFESSIONAL
GUIDANCE OR COUNSEL WITH RESPECT TO THIS CONSENT. I HAVE EITHER SOUGHT SUCH
GUIDANCE OR COUNSEL OR DETERMINED AFTER REVIEWING THE AGREEMENT CAREFULLY THAT I
WILL WAIVE SUCH RIGHT.

     Dated as of the _______ day of ________________, 200__.

                                        ________________________________________
                                        Print name:

                                      II-1<PAGE>

                                                                   EXHIBIT 10.23

                                                 FOR GRANTS TO SENIOR EXECUTIVES
                                       [APPROVED BY THE BOARD OF DIRECTORS 1/05]

                        INCENTIVE STOCK OPTION AGREEMENT

                                 ARCHEMIX CORP.

     AGREEMENT made as of the ___ day of _______ 200_, between Archemix Corp.
(the "Company"), a Delaware corporation having a principal place of business in
Cambridge, Massachusetts, and ____________ of ____________, an employee of the
Company (the "Employee").

     WHEREAS, the Company desires to grant to the Employee an Option to purchase
shares of its common stock, $.001 par value per share (the "Shares"), under and
for the purposes set forth in the Company's 2001 Employee, Director and
Consultant Stock Plan (the "Plan");

     WHEREAS, the Company and the Employee understand and agree that any terms
used and not defined herein have the same meanings as in the Plan; and

     WHEREAS, the Company and the Employee each intend that the Option granted
herein qualify as an ISO.

     NOW, THEREFORE, in consideration of the mutual covenants hereinafter set
forth and for other good and valuable consideration, the parties hereto agree as
follows:

     1. GRANT OF OPTION.

     The Company hereby grants to the Employee the right and option to purchase
all or any part of an aggregate of ________________ Shares, on the terms and
conditions and subject to all the limitations set forth herein, under United
States securities and tax laws, and in the Plan, which is incorporated herein by
reference. The Employee acknowledges receipt of a copy of the Plan.

     2. PURCHASE PRICE.

     The purchase price of the Shares covered by the Option shall be $____ per
Share, subject to adjustment, as provided in the Plan, in the event of a stock
split, reverse stock split or other events affecting the holders of Shares after
the date hereof (the "Purchase Price"). Payment shall be made in accordance with
Paragraph 8 of the Plan.

     3. EXERCISABILITY OF OPTION.

     Subject to the terms and conditions set forth in this Agreement and the
Plan, the Option granted hereby shall become exercisable as follows:

<PAGE>

<TABLE>
<S>                                    <C>
On the first anniversary of the date   up to _________ Shares
   of this Agreement

Every three months thereafter until    an additional _________ Shares
   the fourth anniversary of this
   Agreement.
</TABLE>

     Alternatively, at the election of the Employee, the Option may be exercised
in whole or in part at any time as to Shares which have not yet vested in
accordance with the above schedule; provided however, as a condition to
exercising the Option for such unvested Shares, the Employee shall execute a
Restricted Stock Agreement in the form attached hereto as Exhibit C.

     The foregoing rights are cumulative and are subject to the other terms and
conditions of this Agreement and the Plan.

     4. TERM OF OPTION.

     The Option shall terminate ten years from the date of this Agreement or, if
the Employee owns as of the date hereof more than ten percent of the total
combined voting power of all classes of capital stock of the Company or an
Affiliate, five years from the date of this Agreement, but shall be subject to
earlier termination as provided herein or in the Plan.

     If the Employee ceases to be an employee of the Company or of an Affiliate
(for any reason other than the death or Disability of the Employee or
termination of the Employee's employment for "cause" as defined in the Plan, the
Option may be exercised, if it has not previously terminated, within three
months after the date the Employee ceases to be an employee of the Company or an
Affiliate, or within the originally prescribed term of the Option, whichever is
earlier, but may not be exercised thereafter. In such event, the Option shall be
exercisable only to the extent that the Option has become exercisable and is in
effect at the date of such cessation of employment.

     Notwithstanding the foregoing, in the event of the Employee's Disability or
death within three months after the termination of employment, the Employee or
the Employee's Survivors may exercise the Option within one year after the date
of the Employee's termination of employment, but in no event after the date of
expiration of the term of the Option.

     In the event the Employee's employment is terminated by the Employee's
employer for "cause" as defined in the Plan, the Employee's right to exercise
any unexercised portion of this Option shall cease immediately as of the time
the Employee is notified his or her employment is terminated for "cause," and
this Option shall thereupon terminate. Notwithstanding anything herein to the
contrary, if subsequent to the Employee's termination as an employee, but prior
to the exercise of the Option, the Board of Directors of the Company determines
that, either prior or subsequent to the Employee's termination, the Employee
engaged in conduct which would constitute "cause," then the Employee shall
immediately cease to have any right to exercise the Option and this Option shall
thereupon terminate.

                                        2

<PAGE>

     In the event of the Disability of the Employee, as determined in accordance
with the Plan, the Option shall be exercisable within one year after the
Employee's termination of employment or, if earlier, within the term originally
prescribed by the Option. In such event, the Option shall be exercisable:

     (a)  to the extent that the Option has become exercisable but has not been
          exercised as of the date of Disability; and

     (b)  in the event rights to exercise the Option accrue periodically, to the
          extent of a pro rata portion through the date of Disability of any
          additional vesting rights that would have accrued on the next vesting
          date had the Employee not become Disabled. The proration shall be
          based upon the number of days accrued in the current vesting period
          prior to the date of Disability.

     In the event of the death of the Employee while an employee of the Company
or of an Affiliate, the Option shall be exercisable by the Employee's Survivors
within one year after the date of death of the Employee or, if earlier, within
the originally prescribed term of the Option. In such event, the Option shall be
exercisable:

     (x)  to the extent that the Option has become exercisable but has not been
          exercised as of the date of death; and

     (y)  in the event rights to exercise the Option accrue periodically, to the
          extent of a pro rata portion through the date of death of any
          additional vesting rights that would have accrued on the next vesting
          date had the Employee not died. The proration shall be based upon the
          number of days accrued in the current vesting period prior to the
          Employee's date of death.

     5. METHOD OF EXERCISING OPTION.

     Subject to the terms and conditions of this Agreement, the Option may be
exercised by written notice to the Company or its designee, in substantially the
form of Exhibit A attached hereto. Such notice shall state the number of Shares
with respect to which the Option is being exercised and shall be signed by the
person exercising the Option. Payment of the Purchase Price for such Shares
shall be made in accordance with Paragraph 8 of the Plan. The Company shall
deliver a certificate or certificates representing such Shares as soon as
practicable after the notice shall be received, provided, however, that the
Company may delay issuance of such Shares until completion of any action or
obtaining of any consent, which the Company deems necessary under any applicable
law (including, without limitation, state securities or "blue sky" laws). The
certificate or certificates for the Shares as to which the Option shall have
been so exercised shall be registered in the Company's share register in the
name of the person so exercising the Option (or, if the Option shall be
exercised by the Employee and if the Employee shall so request in the notice
exercising the Option, shall be registered in the name of the Employee and
another person jointly, with right of survivorship) and shall be delivered as
provided above to or upon the written order of the person exercising the Option.
In the event the

                                        3

<PAGE>

Option shall be exercised, pursuant to Section 4 hereof, by any person other
than the Employee, such notice shall be accompanied by appropriate proof of the
right of such person to exercise the Option. All Shares that shall be purchased
upon the exercise of the Option as provided herein shall be fully paid and
nonassessable.

     6. PARTIAL EXERCISE.

     Exercise of this Option to the extent above stated may be made in part at
any time and from time to time within the above limits, except that no
fractional share shall be issued pursuant to this Option.

     7. NON-ASSIGNABILITY.

     The Option shall not be transferable by the Employee otherwise than by will
or by the laws of descent and distribution. The Option shall be exercisable,
during the Employee's lifetime, only by the Employee (or, in the event of legal
incapacity or incompetency, by the Employee's guardian or representative) and
shall not be assigned, pledged or hypothecated in any way (whether by operation
of law or otherwise) and shall not be subject to execution, attachment or
similar process. Any attempted transfer, assignment, pledge, hypothecation or
other disposition of the Option or of any rights granted hereunder contrary to
the provisions of this Section 7, or the levy of any attachment or similar
process upon the Option shall be null and void.

     8. NO RIGHTS AS STOCKHOLDER UNTIL EXERCISE.

     The Employee shall have no rights as a stockholder with respect to Shares
subject to this Agreement until registration of the Shares in the Company's
share register in the name of the Employee. Except as is expressly provided in
the Plan with respect to certain changes in the capitalization of the Company,
no adjustment shall be made for dividends or similar rights for which the record
date is prior to the date of such registration.

     9. ADJUSTMENTS.

     The Plan contains provisions covering the treatment of Options in a number
of contingencies such as stock splits and mergers. Provisions in the Plan for
adjustment with respect to stock subject to Options and the related provisions
with respect to successors to the business of the Company are hereby made
applicable hereunder and are incorporated herein by reference.

     10. TAXES.

     The Employee acknowledges that any income or other taxes due from him or
her with respect to this Option or the Shares issuable pursuant to this Option
shall be the Employee's responsibility.

                                        4

<PAGE>

     In the event of a Disqualifying Disposition (as defined in Section 15
below) or if the Option is converted into a Non-Qualified Option and such
Non-Qualified Option is exercised, the Company may withhold from the Employee's
remuneration, if any, the minimum statutory amount of federal, state and local
withholding taxes attributable to such amount that is considered compensation
includable in such person's gross income. At the Company's discretion, the
amount required to be withheld may be withheld in cash from such remuneration,
or in kind from the Shares otherwise deliverable to the Employee on exercise of
the Option. The Employee further agrees that, if the Company does not withhold
an amount from the Employee's remuneration sufficient to satisfy the Company's
income tax withholding obligation, the Employee will reimburse the Company on
demand, in cash, for the amount under-withheld.

     11. PURCHASE FOR INVESTMENT.

     Unless the offering and sale of the Shares to be issued upon the particular
exercise of the Option shall have been effectively registered under the
Securities Act of 1933, as now in force or hereafter amended (the "1933 Act"),
the Company shall be under no obligation to issue the Shares covered by such
exercise unless and until the following conditions have been fulfilled:

     (a)  The person(s) who exercise the Option shall warrant to the Company, at
          the time of such exercise, that such person(s) are acquiring such
          Shares for their own respective accounts, for investment, and not with
          a view to, or for sale in connection with, the distribution of any
          such Shares, in which event the person(s) acquiring such Shares shall
          be bound by the provisions of the following legend which shall be
          endorsed upon the certificate(s) evidencing the Shares issued pursuant
          to such exercise:

               "The shares represented by this certificate have been taken for
               investment and they may not be sold or otherwise transferred by
               any person, including a pledgee, unless (1) either (a) a
               Registration Statement with respect to such shares shall be
               effective under the Securities Act of 1933, as amended, or (b)
               the Company shall have received an opinion of counsel
               satisfactory to it that an exemption from registration under such
               Act is then available, and (2) there shall have been compliance
               with all applicable state securities laws;" and

     (b)  If the Company so requires, the Company shall have received an opinion
          of its counsel that the Shares may be issued upon such particular
          exercise in compliance with the 1933 Act without registration
          thereunder. Without limiting the generality of the foregoing, the
          Company may delay issuance of the Shares until completion of any
          action or obtaining of any consent, which the Company deems necessary
          under any applicable law (including without limitation state
          securities or "blue sky" laws).

     12. RESTRICTIONS ON TRANSFER OF SHARES.

                                        5

<PAGE>

     12.1 The Shares acquired by the Employee pursuant to the exercise of the
Option granted hereby shall not be transferred by the Employee except as
permitted herein.

     12.2 In the event of the Employee's termination of employment for any
reason, the Company shall have the option, but not the obligation, to repurchase
all or any part of the Shares issued pursuant to this Agreement (including,
without limitation, Shares purchased after termination of employment, Disability
or death in accordance with Section 4 hereof). In the event the Company does
not, upon the termination of employment of the Employee (as described above),
exercise its option pursuant to this Section 12.2, the restrictions set forth in
the balance of this Agreement shall not thereby lapse, and the Employee for
himself or herself, his or her heirs, legatees, executors, administrators and
other successors in interest, agrees that the Shares shall remain subject to
such restrictions. The following provisions shall apply to a repurchase under
this Section 12.2:

     (i)  The per share repurchase price of the Shares to be sold to the Company
          upon exercise of its option under this Section 12.2 shall be equal to
          the Fair Market Value of each such Share determined in accordance with
          the Plan as of the date of termination of employment.

     (ii) The Company's option to repurchase the Employee's Shares in the event
          of termination of employment shall be valid for a period of 18 months
          commencing with the date of such termination of employment.

     (iii) In the event the Company shall be entitled to and shall elect to
          exercise its option to repurchase the Employee's Shares under this
          Section 12.2, the Company shall notify the Employee, or in case of
          death, his or her Survivor, in writing of its intent to repurchase the
          Shares. Such written notice may be mailed by the Company up to and
          including the last day of the time period provided for in Section
          12.2(ii) for exercise of the Company's option to repurchase.

     (iv) The written notice to the Employee shall specify the address at, and
          the time and date on, which payment of the repurchase price is to be
          made (the "Closing"). The date specified shall not be less than ten
          days nor more than 60 days from the date of the mailing of the notice,
          and the Employee or his or her successor in interest with respect to
          the Shares shall have no further rights as the owner thereof from and
          after the date specified in the notice. At the Closing, the repurchase
          price shall be delivered to the Employee or his or her successor in
          interest and the Shares being purchased, duly endorsed for transfer,
          shall, to the extent that they are not then in the possession of the
          Company, be delivered to the Company by the Employee or his or her
          successor in interest.

     12.3 It shall be a condition precedent to the validity of any sale or other
transfer of any Shares by the Employee that the following restrictions be
complied with (except as hereinafter otherwise provided):

                                        6

<PAGE>

     (i)  No Shares owned by the Employee may be sold, pledged or otherwise
          transferred (including by gift or devise) to any person or entity,
          voluntarily, or by operation of law, except in accordance with the
          terms and conditions hereinafter set forth.

     (ii) Before selling or otherwise transferring all or part of the Shares,
          the Employee shall give written notice of such intention to the
          Company, which notice shall include the name of the proposed
          transferee, the proposed purchase price per share, the terms of
          payment of such purchase price and all other matters relating to such
          sale or transfer and shall be accompanied by a copy of the binding
          written agreement of the proposed transferee to purchase the Shares of
          the Employee. Such notice shall constitute a binding offer by the
          Employee to sell to the Company such number of the Shares then held by
          the Employee as are proposed to be sold in the notice at the monetary
          price per share designated in such notice, payable on the terms
          offered to the Employee by the proposed transferee (provided, however,
          that the Company shall not be required to meet any non-monetary terms
          of the proposed transfer, including, without limitation, delivery of
          other securities in exchange for the Shares proposed to be sold). The
          Company shall give written notice to the Employee as to whether such
          offer has been accepted in whole by the Company within 60 days after
          its receipt of written notice from the Employee. The Company may only
          accept such offer in whole and may not accept such offer in part. Such
          acceptance notice shall fix a time, location and date for the closing
          on such purchase ("Closing Date") which shall not be less than ten nor
          more than sixty days after the giving of the acceptance notice,
          provided, however, if any of the Shares to be sold pursuant to this
          Section 12.3 have been held by the Employee for less than six months,
          then the Closing Date may be extended by the Company until no more
          than ten days after such Shares have been held by the Employee for six
          months. The place for such closing shall be at the Company's principal
          office. At such closing, the Employee shall accept payment as set
          forth herein and shall deliver to the Company in exchange therefor
          certificates for the number of Shares stated in the notice accompanied
          by duly executed instruments of transfer.

     (iii) If the Company shall fail to accept any such offer, the Employee
          shall be free to sell all, but not less than all, of the Shares set
          forth in his or her notice to the designated transferee at the price
          and terms designated in the Employee's notice, provided that (i) such
          sale is consummated within six months after the giving of notice by
          the Employee to the Company as aforesaid, and (ii) the transferee
          first agrees in writing to be bound by the provisions of this Section
          12 so that such transferee (and all subsequent transferees) shall
          thereafter only be permitted to sell or transfer the Shares in
          accordance with the terms hereof. After the expiration of such six
          months, the provisions of this Section 12.3 shall again apply with
          respect to any proposed voluntary transfer of the Employee's Shares.

     (iv) The restrictions on transfer contained in this Section 12.3 shall not
          apply to (a) transfers by the Employee to his or her spouse or
          children or to a trust for the benefit of his or her spouse or
          children, (b) transfers by the Employee to his or her

                                        7

<PAGE>

          guardian or conservator, and (c) or transfers by the Employee, in the
          event of his or her death, to his or her executor(s) or
          administrator(s) or to trustee(s) under his or her will (collectively,
          "Permitted Transferees"); provided however, that in any such event the
          Shares so transferred in the hands of each such Permitted Transferee
          shall remain subject to this Agreement, and each such Permitted
          Transferee shall so acknowledge in writing as a condition precedent to
          the effectiveness of such transfer.

     (v)  The provisions of this Section 12.3 may be waived by the Company. Any
          such waiver may be unconditional or based upon such conditions as the
          Company may impose.

     12.4 In the event that the Employee or his or her successor in interest
fails to deliver the Shares to be repurchased by the Company under this
Agreement, the Company may elect (a) to establish a segregated account in the
amount of the repurchase price, such account to be turned over to the Employee
or his or her successor in interest upon delivery of such Shares, and (b)
immediately to take such action as is appropriate to transfer record title of
such Shares from the Employee to the Company and to treat the Employee and such
Shares in all respects as if delivery of such Shares had been made as required
by this Agreement. The Employee hereby irrevocably grants the Company a power of
attorney which shall be coupled with an interest for the purpose of effectuating
the preceding sentence.

     12.5 If the Company shall pay a stock dividend or declare a stock split on
or with respect to any of its Common Stock, or otherwise distribute securities
of the Company to the holders of its Common Stock, the number of shares of stock
or other securities of Company issued with respect to the shares then subject to
the restrictions contained in this Agreement shall be added to the Shares
subject to the Company's rights to repurchase pursuant to this Agreement. If the
Company shall distribute to its stockholders shares of stock of another
corporation, the shares of stock of such other corporation, distributed with
respect to the Shares then subject to the restrictions contained in this
Agreement, shall be added to the Shares subject to the Company's rights to
repurchase pursuant to this Agreement.

     12.6 If the outstanding shares of Common Stock of the Company shall be
subdivided into a greater number of shares or combined into a smaller number of
shares, or in the event of a reclassification of the outstanding shares of
Common Stock of the Company, or if the Company shall be a party to a merger,
consolidation or capital reorganization, there shall be substituted for the
Shares then subject to the restrictions contained in this Agreement such amount
and kind of securities as are issued in such subdivision, combination,
reclassification, merger, consolidation or capital reorganization in respect of
the Shares subject immediately prior thereto to the Company's rights to
repurchase pursuant to this Agreement.

     12.7 The Company shall not be required to transfer any Shares on its books
which shall have been sold, assigned or otherwise transferred in violation of
this Agreement, or to treat as owner of such Shares, or to accord the right to
vote as such owner or to pay dividends to, any person or organization to which
any such Shares shall have been so sold, assigned or otherwise transferred, in
violation of this Agreement.

                                        8

<PAGE>

     12.8 The provisions of Sections 12.1, 12.2 and 12.3 shall terminate upon
the consummation of a public offering of any of the Company's securities
pursuant to a registration statement filed with the Securities and Exchange
Commission.

     12.9 The Employee agrees that in the event that the Company effects an
initial public offering of the Common Stock of the Company registered under the
Securities Act, the Shares may not be sold, offered for sale or otherwise
disposed of, directly or indirectly, without the prior written consent of the
managing underwriter(s) of the offering, for such period of time after the
execution of an underwriting agreement in connection with the such offering that
all of the Company's then directors and executive officers agree to be similarly
bound.

     12.10 The Employee acknowledges and agrees that neither the Company, its
shareholders nor its directors and officers, has any duty or obligation to
disclose to the Employee any material information regarding the business of the
Company or affecting the value of the Shares before, at the time of, or
following a termination of the employment of the Employee by the Company,
including, without limitation, any information concerning plans for the Company
to make a public offering of its securities or to be acquired by or merged with
or into another firm or entity.

     12.11 All certificates representing the Shares to be issued to the Employee
pursuant to this Agreement shall have endorsed thereon a legend substantially as
follows: "The shares represented by this certificate are subject to restrictions
set forth in an Incentive Stock Option Agreement dated _________, 200__ with
this Company, a copy of which Agreement is available for inspection at the
offices of the Company or will be made available upon request."

     13. NO OBLIGATION TO EMPLOY.

     The Company is not by the Plan or this Option obligated to continue the
Employee as an employee of the Company or an Affiliate. The Employee
acknowledges: (i) that the Plan is discretionary in nature and may be suspended
or terminated by the Company at any time; (ii) that the grant of the Option is a
one-time benefit which does not create any contractual or other right to receive
future grants of options, or benefits in lieu of options; (iii) that all
determinations with respect to any such future grants, including, but not
limited to, the times when options shall be granted, the number of shares
subject to each option, the option price, and the time or times when each option
shall be exercisable, will be at the sole discretion of the Company; (iv) that
the Employee's participation in the Plan is voluntary; (v) that the value of the
Option is an extraordinary item of compensation which is outside the scope of
the Employee's employment contract, if any; and (vi) that the Option is not part
of normal or expected compensation for purposes of calculating any severance,
resignation, redundancy, end of service payments, bonuses, long-service awards,
pension or retirement benefits or similar payments.

     14. OPTION IS INTENDED TO BE AN ISO.

     The parties each intend that the Option be an ISO so that the Employee (or
the Employee's Survivors) may qualify for the favorable tax treatment provided
to holders of

                                        9

<PAGE>

Options that meet the standards of Section 422 of the Code. Any provision of
this Agreement or the Plan which conflicts with the Code so that this Option
would not be deemed an ISO is null and void and any ambiguities shall be
resolved so that the Option qualifies as an ISO. Nonetheless, if the Option is
determined not to be an ISO, the Employee understands that neither the Company
nor any Affiliate is responsible to compensate him or her or otherwise make up
for the treatment of the Option as a Non-qualified Option and not as an ISO. The
Employee should consult with the Employee's own tax advisors regarding the tax
effects of the Option and the requirements necessary to obtain favorable tax
treatment under Section 422 of the Code, including, but not limited to, holding
period requirements.

     15. NOTICE TO COMPANY OF DISQUALIFYING DISPOSITION.

     The Employee agrees to notify the Company in writing immediately after the
Employee makes a Disqualifying Disposition of any of the Shares acquired
pursuant to the exercise of the Option. A Disqualifying Disposition is defined
in Section 424(c) of the Code and includes any disposition (including any sale)
of such Shares before the later of (a) two years after the date the Employee was
granted the Option or (b) one year after the date the Employee acquired Shares
by exercising the Option, except as otherwise provided in Section 424(c) of the
Code. If the Employee has died before the Shares are sold, these holding period
requirements do not apply and no Disqualifying Disposition can occur thereafter.

     16. NOTICES.

     Any notices required or permitted by the terms of this Agreement or the
Plan shall be given by recognized courier service, facsimile, registered or
certified mail, return receipt requested, addressed as follows:

If to the Company:

          Archemix Corp.
          300 Third Street
          Cambridge, MA 02142
          Attn: President

If to the Employee:

          ______________________________________

          _______________________________________

          _______________________________________

or to such other address or addresses of which notice in the same manner has
previously been given. Any such notice shall be deemed to have been given upon
the earlier of receipt, one business day following delivery to a recognized
courier service or three business days following mailing by registered or
certified mail.

                                       10

<PAGE>

     17. GOVERNING LAW; CONSENT TO JURISDICTION.

     This Agreement shall be construed and enforced in accordance with the law
of the State of Delaware, without giving effect to the conflict of law
principles thereof. For the purpose of litigating any dispute that arises under
this Agreement, the parties hereby consent to exclusive jurisdiction in the
Commonwealth of Massachusetts and agree that such litigation shall be conducted
in the courts of Middlesex County, Massachusetts or the federal courts of the
United States for the District of Massachusetts.

     18. BENEFIT OF AGREEMENT.

     Subject to the provisions of the Plan and the other provisions hereof, this
Agreement shall be for the benefit of and shall be binding upon the heirs,
executors, administrators, successors and assigns of the parties hereto.

     19. ENTIRE AGREEMENT.

     This Agreement, together with the Plan, embodies the entire agreement and
understanding between the parties hereto with respect to the subject matter
hereof and supersedes all prior oral or written agreements and understandings
relating to the subject matter hereof. No statement, representation, warranty,
covenant or agreement not expressly set forth in this Agreement shall affect or
be used to interpret, change or restrict, the express terms and provisions of
this Agreement, provided, however, in any event, this Agreement shall be subject
to and governed by the Plan.

     20. MODIFICATIONS AND AMENDMENTS.

     The terms and provisions of this Agreement may be modified or amended as
provided in the Plan.

     21. WAIVERS AND CONSENTS.

     Except as provided in the Plan, the terms and provisions of this Agreement
may be waived, or consent for the departure therefrom granted, only by written
document executed by the party entitled to the benefits of such terms or
provisions. No such waiver or consent shall be deemed to be or shall constitute
a waiver or consent with respect to any other terms or provisions of this
Agreement, whether or not similar. Each such waiver or consent shall be
effective only in the specific instance and for the purpose for which it was
given, and shall not constitute a continuing waiver or consent.

                                       11

<PAGE>

     22. DATA PRIVACY.

     By entering into this Agreement, the Employee: (i) authorizes the Company
and each Affiliate, and any agent of the Company or any Affiliate administering
the Plan or providing Plan recordkeeping services, to disclose to the Company or
any of its Affiliates such information and data as the Company or any such
Affiliate shall request in order to facilitate the grant of options and the
administration of the Plan; (ii) waives any data privacy rights he or she may
have with respect to such information; and (iii) authorizes the Company and each
Affiliate to store and transmit such information in electronic form.

     23. CONSENT OF SPOUSE.

     If the Employee is married as of the date of this Agreement, the Employee's
spouse shall execute a Consent of Spouse in the form of Exhibit B hereto,
effective as of the date hereof. Such consent shall not be deemed to confer or
convey to the spouse any rights in the Shares that do not otherwise exist by
operation of law or the agreement of the parties. If the Employee marries or
remarries subsequent to the date hereof, the Employee shall, not later than 60
days thereafter, obtain his or her new spouse's acknowledgement of and consent
to the existence and binding effect of Section 12.2 of this Agreement by such
spouse's executing and delivering a Consent of Spouse in the form of Exhibit B.

                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]

                                       12

<PAGE>

     IN WITNESS WHEREOF, the Company has caused this Agreement to be executed by
its duly authorized officer, and the Employee has hereunto set his or her hand,
all as of the day and year first above written.

                                        ARCHEMIX CORP.

                                        By:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------

                                        ----------------------------------------
                                        Employee

                                       13

<PAGE>

                                                                       Exhibit A

                  NOTICE OF EXERCISE OF INCENTIVE STOCK OPTION

                         [FORM FOR UNREGISTERED SHARES]

To: Archemix Corp.

Ladies and Gentlemen:

     I hereby exercise my Incentive Stock Option to purchase ___________ shares
(the "Shares") of the common stock, $.001 par value, of Archemix Corp. (the
"Company"), at the exercise price of $____ per share, pursuant to and subject to
the terms of that certain Incentive Stock Option Agreement between the
undersigned and the Company dated _________, 200_.

     I am aware that the Shares have not been registered under the Securities
Act of 1933, as amended (the "1933 Act"), or any state securities laws. I
understand that the reliance by the Company on exemptions under the 1933 Act is
predicated in part upon the truth and accuracy of the statements by me in this
Notice of Exercise.

     I hereby represent and warrant that (1) I have been furnished with all
information which I deem necessary to evaluate the merits and risks of the
purchase of the Shares; (2) I have had the opportunity to ask questions
concerning the Shares and the Company and all questions posed have been answered
to my satisfaction; (3) I have been given the opportunity to obtain any
additional information I deem necessary to verify the accuracy of any
information obtained concerning the Shares and the Company; and (4) I have such
knowledge and experience in financial and business matters that I am able to
evaluate the merits and risks of purchasing the Shares and to make an informed
investment decision relating thereto.

     I hereby represent and warrant that I am purchasing the Shares for my own
personal account for investment and not with a view to the sale or distribution
of all or any part of the Shares.

     I understand that because the Shares have not been registered under the
1933 Act, I must continue to bear the economic risk of the investment for an
indefinite time and the Shares cannot be sold unless the Shares are subsequently
registered under applicable federal and state securities laws or an exemption
from such registration requirements is available.

     I agree that I will in no event sell or distribute or otherwise dispose of
all or any part of the Shares unless (1) there is an effective registration
statement under the 1933 Act and applicable state securities laws covering any
such transaction involving the Shares or (2) the Company receives an opinion of
my legal counsel (concurred in by legal counsel for the Company) stating that
such transaction is exempt from registration or the Company otherwise satisfies
itself that such transaction is exempt from registration.

                                       A-1

<PAGE>

     I consent to the placing of a legend on my certificate for the Shares
stating that the Shares have not been registered and setting forth the
restriction on transfer contemplated hereby and to the placing of a stop
transfer order on the books of the Company and with any transfer agents against
the Shares until the Shares may be legally resold or distributed without
restriction.

     I understand that at the present time Rule 144 of the Securities and
Exchange Commission (the "SEC") may not be relied on for the resale or
distribution of the Shares by me. I understand that the Company has no
obligation to me to register the sale of the Shares with the SEC and has not
represented to me that it will register the sale of the Shares.

     I understand the terms and restrictions on the right to dispose of the
Shares set forth in the 2001 Employee, Director and Consultant Stock Plan and
the Incentive Stock Option Agreement, both of which I have carefully reviewed. I
consent to the placing of a legend on my certificate for the Shares referring to
such restriction and the placing of stop transfer orders until the Shares may be
transferred in accordance with the terms of such restrictions.

     I have considered the Federal, state and local income tax implications of
the exercise of my Option and the purchase and subsequent sale of the Shares.

     I am paying the option exercise price for the Shares as follows:

                      ___________________________________

     Please issue the stock certificate for the Shares (check one):

     [ ]  to me; or

     [ ]  to me and ________________, as joint tenants with right of
          survivorship

and mail the certificate to me at the following address:

_____________________________________

_____________________________________

_____________________________________

                                       A-2

<PAGE>

     My mailing address for shareholder communications, if different from the
address listed above is:

_____________________________________

_____________________________________

_____________________________________

                                        Very truly yours,

                                        ----------------------------------------
                                        Employee (signature)

                                        ----------------------------------------
                                        Print Name

                                        ----------------------------------------
                                        Date

                                        ----------------------------------------
                                        Social Security Number

                                       A-3

<PAGE>

                                                                       Exhibit A

                  NOTICE OF EXERCISE OF INCENTIVE STOCK OPTION

                          [FORM FOR REGISTERED SHARES]

TO: Archemix Corp.

IMPORTANT NOTICE: This form of Notice of Exercise may only be used at such time
as the Company has filed a Registration Statement with the Securities and
Exchange Commission under which the issuance of the Shares for which this
exercise is being made is registered and such Registration Statement remains
effective.

Ladies and Gentlemen:

     I hereby exercise my Incentive Stock Option to purchase _________ shares
(the "Shares") of the common stock, $.001 par value, of Archemix Corp. (the
"Company"), at the exercise price of $________ per share, pursuant to and
subject to the terms of that certain Incentive Stock Option Agreement between
the undersigned and the Company dated _______________, 200_.

     I understand the nature of the investment I am making and the financial
risks thereof. I am aware that it is my responsibility to have consulted with
competent tax and legal advisors about the relevant national, state and local
income tax and securities laws affecting the exercise of the Option and the
purchase and subsequent sale of the Shares.

     I am paying the option exercise price for the Shares as follows:

                      ____________________________________

     Please issue the Shares (check one):

     [ ]  to me; or

     [ ]  to me and ____________________________, as joint tenants with right of
          survivorship,

     at the following address:

_____________________________________

_____________________________________

_____________________________________

                                       A-1

<PAGE>

     My mailing address for shareholder communications, if different from the
address listed above, is:

_____________________________________

_____________________________________

_____________________________________

                                        Very truly yours,

                                        ----------------------------------------
                                        Employee (signature)

                                        ----------------------------------------
                                        Print Name

                                        ----------------------------------------
                                        Date

                                        ----------------------------------------
                                        Social Security Number

                                       A-2

<PAGE>

                                                                       Exhibit B

                                CONSENT OF SPOUSE

     I, ____________________________, spouse of _____________________________,
acknowledge that I have read the Incentive Stock Option Agreement dated as of
_______________, 200__ (the "Agreement") to which this Consent is attached as
Exhibit B and that I know its contents. Capitalized terms used and not defined
herein shall have the meanings assigned to such terms in the Agreement. I am
aware that by its provisions the Shares granted to my spouse pursuant to the
Agreement are subject to a right of repurchase in favor of Archemix Corp. (the
"Company") and that, accordingly, the Company has the right to repurchase up to
all of the Shares of which I may become possessed as a result of a gift from my
spouse or a court decree and/or any property settlement in any domestic
litigation.

     I hereby agree that my interest, if any, in the Shares subject to the
Agreement shall be irrevocably bound by the Agreement and further understand and
agree that any community property interest I may have in the Shares shall be
similarly bound by the Agreement.

     I agree to the repurchase right described in Section 12.2 of the Agreement
and I hereby consent to the repurchase of the Shares by the Company and the sale
of the Shares by my spouse or my spouse's legal representative in accordance
with the provisions of the Agreement. Further, as part of the consideration for
the Agreement, I agree that at my death, if I have not disposed of any interest
of mine in the Shares by an outright bequest of the Shares to my spouse, then
the Company shall have the same rights against my legal representative to
exercise its rights of repurchase with respect to any interest of mine in the
Shares as it would have had pursuant to the Agreement if I had acquired the
Shares pursuant to a court decree in domestic litigation.

     I AM AWARE THAT THE LEGAL, FINANCIAL AND RELATED MATTERS CONTAINED IN THE
AGREEMENT ARE COMPLEX AND THAT I AM FREE TO SEEK INDEPENDENT PROFESSIONAL
GUIDANCE OR COUNSEL WITH RESPECT TO THIS CONSENT. I HAVE EITHER SOUGHT SUCH
GUIDANCE OR COUNSEL OR DETERMINED AFTER REVIEWING THE AGREEMENT CAREFULLY THAT I
WILL WAIVE SUCH RIGHT.

     Dated as of the _______ day of ________________, 200__.

                                        ----------------------------------------
                                        Print name:

                                       B-1

<PAGE>

                                                                       EXHIBIT C

                           RESTRICTED STOCK AGREEMENT

                                 ARCHEMIX CORP.

     AGREEMENT made as of the ___ day of ____________, 200__ (the "Grant Date"),
between Archemix Corp. (the "Company"), a Delaware corporation having its
principal place of business in Cambridge, Massachusetts, and ________________ of
________________________, (the "Participant").

     WHEREAS, the Company has adopted the Archemix Corp. 2001 Employee, Director
and Consultant Stock Plan (the "Plan") to promote the interests of the Company
by providing an incentive for employees, directors and consultants of the
Company or its Affiliates;

     WHEREAS, the parties hereto understand and agree that any terms used and
not defined herein have the meanings ascribed to such terms in the Plan and that
any and all references herein to employment of the Participant by the Company
shall include the Participant's employment or service as an employee, director
or consultant of the Company or any Affiliate;

     WHEREAS, pursuant to the exercise of an option granted to the Participant
pursuant to an Incentive Stock Option Agreement dated ___________ by and between
the Company and the Participant issued under the Plan (the "Option Agreement"),
which Option Agreement and Plan are hereby incorporated herein by reference, the
Participant has elected to purchase _________ shares of the Company's common
stock, $.001 par value per share ("Common Stock"), which have not become vested
under the vesting schedule set forth in the Option Agreement (the "Unvested
Shares"). The Unvested Shares and the Shares subject to the Option Agreement
that have become vested are sometimes collectively referred to herein as the
"Shares."

     WHEREAS, as required by the Option Agreement, as a condition to the
Participant's election to exercise the option, the Participant must execute this
Agreement, which sets forth the rights and obligations of the parties with
respect to the Unvested Shares acquired upon exercise of the option pursuant to
the Option Agreement; and

     WHEREAS, Participant wishes to accept said offer in accordance with the
provisions of the Plan, all on the terms and conditions hereinafter set forth.

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

                                       C-1

<PAGE>

     1. Company's Lapsing Repurchase Right.

     (a) Lapsing Repurchase Right. Except as set forth in Subsection 1(b)
hereof, in the event that for any reason the Participant no longer is an
employee, director or consultant of the Company or an Affiliate, the Company (or
its designee) shall have the option, but not the obligation, to purchase from
the Participant (or the Participant's Survivor), and, in the event the Company
exercises such option, the Participant (or the Participant's Survivor) shall be
obligated to sell to the Company (or its designee), at a price per Share equal
to the Purchase Price, all or any part of the Unvested Shares determined as of
the date of such termination of service (the "Lapsing Repurchase Right"). The
Lapsing Repurchase Right with respect to the Unvested Shares shall terminate as
to such Unvested Shares in accordance with the vesting schedule set forth in
Section 3 of the Option Agreement. The Company's Lapsing Repurchase Right shall
be valid for a period of one year commencing with the date of such termination
of employment or service. Notwithstanding any other provision hereof, in the
event the Company is prohibited during such one year period from exercising its
Lapsing Repurchase Right by applicable law, then the time period during which
such Lapsing Repurchase Right may be exercised shall be extended until 30 days
after the Company is first not so prohibited.

     (b) Effect of Termination for Disability or upon Death. The following rules
apply if the Participant ceases to be an employee, director or consultant of the
Company by reason of Disability or death: to the extent the Company's Lapsing
Repurchase Right has not lapsed as of the date of Disability or death, as case
may be, the Company may exercise such Lapsing Repurchase Right; provided,
however, that the Company's Lapsing Repurchase Right shall be deemed to have
lapsed to the extent of a pro rata portion of the Unvested Shares through the
date of Disability or death, as would have lapsed had the Participant not become
Disabled or died, as the case may be. The proration shall be based upon the
number of days accrued in such current vesting period prior to the Participant's
date of Disability or death, as the case may be.

     (c) Closing. In the event that the Company exercises the Lapsing Repurchase
Right, the Company shall notify the Participant, or, in the case of the
Participant's death, his or her Survivor, in writing of its intent to repurchase
the Unvested Shares. Such notice may be mailed by the Company up to and
including the last day of the time period provided for above for exercise of the
Lapsing Repurchase Right. The notice shall specify the place, time and date for
payment of the repurchase price (the "Closing") and the number of Unvested
Shares with respect to which the Company is exercising the Lapsing Repurchase
Right. The Closing shall be not less than ten days nor more than 60 days from
the date of mailing of the notice, and the Participant or the Participant's
Survivor with respect to the Unvested Shares which the Company elects to
repurchase shall have no further rights as the owner thereof from and after the
date specified in the notice. At the Closing, the repurchase price shall be
delivered to the Participant or the Participant's Survivor and the Unvested
Shares being repurchased, duly endorsed for transfer, shall, to the extent that
they are not then in the possession of the Company, be delivered to the Company
by the Participant or the Participant's Survivor.

     (d) Escrow. The certificates representing all Unvested Shares acquired by
the Participant hereunder which from time to time are subject to the Lapsing
Repurchase Right shall be delivered to the Company and the Company shall hold
such Unvested Shares in escrow as

                                       C-2

<PAGE>

provided in this Subsection 1(d). Promptly following receipt by the Company of a
written request from the Participant, the Company shall release from escrow and
deliver to the Participant a certificate for the whole number of Unvested
Shares, if any, as to which the Company's Lapsing Repurchase Right has lapsed.
In the event of a repurchase by the Company of Unvested Shares subject to the
Lapsing Repurchase Right, the Company shall release from escrow and cancel a
certificate for the number of Unvested Shares so repurchased. Any securities
distributed in respect of the Unvested Shares held in escrow, including, without
limitation, shares issued as a result of stock splits, stock dividends or other
recapitalizations, shall also be held in escrow in the same manner as the
Unvested Shares.

     (e) Prohibition on Transfer. The Participant recognizes and agrees that all
Unvested Shares which are subject to the Lapsing Repurchase Right may not be
sold, transferred, assigned, hypothecated, pledged, encumbered or otherwise
disposed of, whether voluntarily or by operation of law, other than to the
Company (or its designee). The Company shall not be required to transfer any
Unvested Shares on its books which shall have been sold, assigned or otherwise
transferred in violation of this Subsection 1(e), or to treat as the owner of
such Unvested Shares, or to accord the right to vote as such owner or to pay
dividends to, any person or organization to which any such Unvested Shares shall
have been so sold, assigned or otherwise transferred, in violation of this
Subsection 1(e). The Participant further recognizes and agrees that all Shares
remain subject to Section 12 of the Option Agreement, except that with respect
to the Unvested Shares subject to the Lapsing Repurchase Right, this Agreement
will supercede Section 12.3 of the Option Agreement.

     (f) Failure to Deliver Unvested Shares to be Repurchased. In the event that
the Unvested Shares to be repurchased by the Company under this Agreement are
not in the Company's possession pursuant to Subsection 1(d) above or otherwise
and the Participant or the Participant's Survivor fails to deliver such Unvested
Shares to the Company (or its designee), the Company may elect (i) to establish
a segregated account in the amount of the repurchase price, such account to be
turned over to the Participant or the Participant's Survivor upon delivery of
such Unvested Shares, and (ii) immediately to take such action as is appropriate
to transfer record title of such Unvested Shares from the Participant to the
Company (or its designee) and to treat the Participant and such Unvested Shares
in all respects as if delivery of such Unvested Shares had been made as required
by this Agreement. The Participant hereby irrevocably grants the Company a power
of attorney which shall be coupled with an interest for the purpose of
effectuating the preceding sentence.

     (g) Adjustments. The Plan contains provisions covering the treatment of
Shares in a number of contingencies such as stock splits and mergers. Provisions
in the Plan for adjustment with respect to the Shares and the related provisions
with respect to successors to the business of the Company are hereby made
applicable hereunder and are incorporated herein by reference.

     2. Legend. In addition to any legend required pursuant to the Plan or the
Option Agreement, all certificates representing the Unvested Shares to be issued
to the Participant pursuant to this Agreement shall have endorsed thereon a
legend substantially as follows:

                                       C-3

<PAGE>

          "The shares represented by this certificate are subject to
          restrictions set forth in a Restricted Stock Agreement dated as of
          ____________, 200__ with this Company, a copy of which Agreement is
          available for inspection at the offices of the Company or will be made
          available upon request."

     3. Purchase for Investment. If the offering and sale of the Unvested Shares
have not been effectively registered under the Securities Act of 1933, as
amended, the Participant hereby represents and warrants that he or she is
acquiring the Unvested Shares for his or her own account, for investment, and
not with a view to, or for sale in connection with, the distribution of any such
Unvested Shares.

     4. Provisions of Agreement Controlling. The Participant specifically
understands and agrees that the Unvested Shares issued under the Plan are being
sold to the Participant pursuant to the Plan and the Option Agreement, a copy of
which Plan and Option Agreement the Participant acknowledges he or she has read
and understands and by which Plan and Option Agreement he or she agrees to be
bound. The provisions of the Plan and the Option Agreement are incorporated
herein by reference. In the event of a conflict between the terms and conditions
of the Plan, this Agreement and the Option Agreement, the provisions of this
Agreement will control.

     5. Tax Liability of the Participant and Payment of Taxes. The Participant
acknowledges and agrees that any income or other taxes due from the Participant
with respect to the Unvested Shares issued pursuant to this Agreement,
including, without limitation, the Lapsing Repurchase Right, shall be the
Participant's responsibility. Without limiting the foregoing, the Participant
agrees that, to the extent that the lapsing of restrictions on disposition of
any of the Unvested Shares or the declaration of dividends on any such shares
before the lapse of such restrictions on disposition results in the
Participant's being deemed to be in receipt of earned income under the
provisions of the Code, the Company shall be entitled to immediate payment from
the Participant of the amount of any tax required to be withheld by the Company.

     Upon execution of this Agreement, the Participant may file an election
under Section 83 of the Code in substantially the form attached as Attachment I.
The Participant acknowledges that if she does not file such an election, as the
Unvested Shares are released from the Lapsing Repurchase Right in accordance
with Section 1, the Participant may have income for tax purposes equal to the
fair market value of the Unvested Shares at such date, less the price paid for
the Unvested Shares by the Participant.

     6. Securities Law Compliance. The Participant specifically acknowledges and
agrees that any sales of Unvested Shares shall be made in accordance with the
requirements of the Securities Act of 1933, as amended, in a transaction as to
which the Company shall have received an opinion of counsel satisfactory to it
confirming such compliance.

     7. Equitable Relief. The Participant specifically acknowledges and agrees
that in the event of a breach or threatened breach of the provisions of this
Agreement, the Option Agreement or the Plan, including the attempted transfer of
the Unvested Shares by the Participant in violation of this Agreement or the
Option Agreement, monetary damages may not

                                       C-4

<PAGE>

be adequate to compensate the Company, and, therefore, in the event of such a
breach or threatened breach, in addition to any right to damages, the Company
shall be entitled to equitable relief in any court having competent
jurisdiction. Nothing herein shall be construed as prohibiting the Company from
pursuing any other remedies available to it for any such breach or threatened
breach.

     8. No Obligation to Maintain Relationship. The Company is not by the Plan,
the Option Agreement or this Agreement obligated to continue the Participant as
an employee, director or consultant of the Company. The Participant
acknowledges: (i) that the Plan is discretionary in nature and may be suspended
or terminated by the Company at any time; (ii) that the grant of the Shares is a
one-time benefit which does not create any contractual or other right to receive
future grants of shares, or benefits in lieu of shares; (iii) that all
determinations with respect to any such future grants, including, but not
limited to, the times when shares shall be granted, the number of shares to be
granted, the Purchase Price, and the time or times when each share shall be free
from the Lapsing Repurchase Right, will be at the sole discretion of the
Company; (iv) that the Participant's participation in the Plan is voluntary; (v)
that the value of the Shares is an extraordinary item of compensation which is
outside the scope of the Participant's employment contract, if any; and (vi)
that the Shares are not part of normal or expected compensation for purposes of
calculating any severance, resignation, redundancy, end of service payments,
bonuses, long-service awards, pension or retirement benefits or similar
payments.

     9. Notices. Any notices required or permitted by the terms of this
Agreement, the Option Agreement or the Plan shall be given by recognized courier
service, facsimile, registered or certified mail, return receipt requested,
addressed as follows:

     If to the Company:

          Archemix Corp.
          300 Third Street
          Cambridge, MA 02142
          Attn: President

     If to the Participant:

          _________________________________________

          _________________________________________

          _________________________________________

or to such other address or addresses of which notice in the same manner has
previously been given. Any such notice shall be deemed to have been given on the
earliest of receipt, one business day following delivery by the sender to a
recognized courier service, or three business days following mailing by
registered or certified mail.

                                       C-5

<PAGE>

     10. Binding Effect. This Agreement shall be for the benefit of and shall be
binding upon the parties hereto, upon their respective successors and assigns
and upon the Participant's heirs, executors, administrators.

     11. Governing Law; Consent to Jurisdiction. This Agreement shall be
construed and enforced in accordance with the law of the State of Delaware,
without giving effect to the conflict of law principles thereof. For the purpose
of litigating any dispute that arises under this Agreement, the parties hereby
consent to exclusive jurisdiction in the Commonwealth of Massachusetts and agree
that such litigation shall be conducted in the courts of Middlesex County,
Massachusetts or the federal courts of the United States for the District of
Massachusetts.

     12. Severability. If any provision of this Agreement is held to be invalid
or unenforceable by a court of competent jurisdiction, then such provision or
provisions shall be modified to the extent necessary to make such provision
valid and enforceable, and to the extent that this is impossible, then such
provision shall be deemed to be excised from this Agreement, and the validity,
legality and enforceability of the rest of this Agreement shall not be affected
thereby.

     13. Entire Agreement. This Agreement, together with the Plan and the Option
Agreement, constitutes the entire agreement and understanding between the
parties hereto with respect to the subject matter hereof and supersedes all
prior oral or written agreements and understandings relating to the subject
matter hereof. No statement, representation, warranty, covenant or agreement not
expressly set forth in this Agreement, the Option Agreement or the Plan shall
affect or be used to interpret, change or restrict the express terms and
provisions of this Agreement provided, however, in any event, this Agreement
shall be subject to and governed by the Plan.

     14. Modifications and Amendments; Waivers and Consents. The terms and
provisions of this Agreement may be modified or amended as provided in the Plan.
Except as provided in the Plan, the terms and provisions of this Agreement may
be waived, or consent for the departure therefrom granted, only by written
document executed by the party entitled to the benefits of such terms or
provisions. No such waiver or consent shall be deemed to be or shall constitute
a waiver or consent with respect to any other terms or provisions of this
Agreement, whether or not similar. Each such waiver or consent shall be
effective only in the specific instance and for the purpose for which it was
given, and shall not constitute a continuing waiver or consent.

     15. Consent of Spouse. If the Participant is married as of the date of this
Agreement, the Participant's spouse shall execute a Consent of Spouse in the
form of Attachment II hereto, effective as of the date hereof. Such consent
shall not be deemed to confer or convey to the spouse any rights in the Unvested
Shares that do not otherwise exist by operation of law or the agreement of the
parties. If the Participant marries or remarries subsequent to the date hereof,
the Participant shall, not later than 60 days thereafter, obtain his or her new
spouse's acknowledgement of and consent to the existence and binding effect of
all restrictions contained

                                       C-6

<PAGE>

in this Agreement by such spouse's executing and delivering a Consent of Spouse
in the form of Attachment II.

     16. Counterparts. This Agreement may be executed in one or more
counterparts, and by different parties hereto on separate counterparts, each of
which shall be deemed an original, but all of which together shall constitute
one and the same instrument.

     17. Data Privacy. By entering into this Agreement, the Participant: (i)
authorizes the Company and each Affiliate, and any agent of the Company or any
Affiliate administering the Plan or providing Plan record keeping services, to
disclose to the Company or any of its Affiliates such information and data as
the Company or any such Affiliate shall request in order to facilitate the grant
of Shares and the administration of the Plan; (ii) waives any data privacy
rights he or she may have with respect to such information; and (iii) authorizes
the Company and each Affiliate to store and transmit such information in
electronic form.

                      [THE NEXT PAGE IS THE SIGNATURE PAGE]

                                       C-7

<PAGE>

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

                                        ARCHEMIX CORP.

                                        By:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------

                                        PARTICIPANT:

                                        ----------------------------------------
                                        Print name:

                                       C-8

<PAGE>

                                                                    ATTACHMENT I

                    ELECTION TO INCLUDE GROSS INCOME IN YEAR
                      OF TRANSFER PURSUANT TO SECTION 83(B)
                OF THE INTERNAL REVENUE CODE OF 1986, AS AMENDED

     In accordance with Section 83(b) of the Internal Revenue Code of 1986, as
amended (the "Code"), the undersigned hereby elects to include in his gross
income as compensation for services the excess, if any, of the fair market value
of the property (described below) at the time of transfer over the amount paid
for such property.

The following sets for the information required in accordance with the Code and
the regulations promulgated hereunder:

1.   The name, address and social security number of the undersigned are:

     Name: _____________________________
     Address: __________________________
     Social Security No.: ______________

2.   The description of the property with respect to which the election is being
     made is as follows:

     ____________ (___) shares (the "Shares") of Common Stock, $.001 par value
     per share, of Archemix Corp., a Delaware corporation (the "Company").

3.   This election is made for the calendar year ____, with respect to the
     transfer of the property to the Taxpayer on _______________.

4.   Description of restrictions: The property is subject to the following
     restrictions:

     In the event taxpayer's employment with the Company or an Affiliate is
     terminated, the Company may repurchase all or any portion of the Shares
     determined as set forth below at the acquisition price paid by the
     taxpayer:

     A.   If the termination takes place on or prior to ____________, the
          Purchase Option will apply to all of the Shares.

     B.   If the termination takes place after __________, 200_, the number of
          Shares to which the Purchase Option applies shall be ______________
          (___) Shares less ____________________ (___) Shares for each full
          twelve (12) month period elapsed after _____________, 200_ if the
          taxpayer is employed by the Company or an Affiliate.

                                       I-1

<PAGE>

5.   The fair market value at time of transfer (determined without regard to any
     restrictions other than restrictions which by their terms will never lapse)
     of the property with respect to which this election is being made was not
     more than $____ per Share.

6.   The amount paid by taxpayer for said property was $___ per Share.

7.   A copy of this statement has been furnished to the Company.

Signed this ____ day of ______, 200_.

                                        ----------------------------------------
                                        Print Name:

                                       I-2

<PAGE>

                                                                   ATTACHMENT II

                                CONSENT OF SPOUSE

     I, ____________________________, spouse of _____________________________,
acknowledge that I have read the RESTRICTED STOCK AGREEMENT dated as of
_______________, 200__ (the "Agreement") to which this Consent is attached as
Attachment II and that I know its contents. Capitalized terms used and not
defined herein shall have the meanings assigned to such terms in the Agreement.
I am aware that by its provisions the Unvested Shares granted to my spouse
pursuant to the Agreement are subject to a Lapsing Repurchase Right in favor of
Archemix Corp. (the "Company") and that, accordingly, the Company has the right
to repurchase up to all of the Unvested Shares of which I may become possessed
as a result of a gift from my spouse or a court decree and/or any property
settlement in any domestic litigation.

     I hereby agree that my interest, if any, in the Unvested Shares subject to
the Agreement shall be irrevocably bound by the Agreement and further understand
and agree that any community property interest I may have in the Unvested Shares
shall be similarly bound by the Agreement.

     I agree to the Lapsing Repurchase Right described in the Agreement and I
hereby consent to the repurchase of the Unvested Shares by the Company and the
sale of the Unvested Shares by my spouse or my spouse's legal representative in
accordance with the provisions of the Agreement. Further, as part of the
consideration for the Agreement, I agree that at my death, if I have not
disposed of any interest of mine in the Unvested Shares by an outright bequest
of the Unvested Shares to my spouse, then the Company shall have the same rights
against my legal representative to exercise its rights of repurchase with
respect to any interest of mine in the Unvested Shares as it would have had
pursuant to the Agreement if I had acquired the Unvested Shares pursuant to a
court decree in domestic litigation.

     I AM AWARE THAT THE LEGAL, FINANCIAL AND RELATED MATTERS CONTAINED IN THE
AGREEMENT ARE COMPLEX AND THAT I AM FREE TO SEEK INDEPENDENT PROFESSIONAL
GUIDANCE OR COUNSEL WITH RESPECT TO THIS CONSENT. I HAVE EITHER SOUGHT SUCH
GUIDANCE OR COUNSEL OR DETERMINED AFTER REVIEWING THE AGREEMENT CAREFULLY THAT I
WILL WAIVE SUCH RIGHT.

     Dated as of the _______ day of ________________, 200__.

                                        ----------------------------------------
                                        Print name:

                                      II-1

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