Document:

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                                                                    Exhibit 10.1

                                 HYBRIDON, INC.

                              EMPLOYMENT AGREEMENT

      THIS EMPLOYMENT AGREEMENT ("Agreement") is entered into by and between
Sudhir Agrawal ("Executive") and Hybridon, Inc., a Delaware corporation (the
"Company"), and is effective as of the 1st day of April, 2002.

      WHEREAS, the Company desires to establish its right to the services of
Executive, in the capacity described below, on the terms and conditions
hereinafter set forth, and Executive is willing to accept such employment on
such terms and conditions;

      NOW, THEREFORE, in consideration of the mutual agreements hereinafter set
forth, Executive and the Company have agreed and do hereby agree as follows:

      1. Definitions.  The capitalized terms in this Agreement shall have the
meanings set forth in this Agreement or Appendix A attached hereto.

      2. Engagement.  The Company hereby agrees to employ Executive as its
President and Chief Scientific Officer and the Executive hereby accepts such
employment on the terms and conditions hereinafter set forth.

      3. Employment Period. The Executive's employment with the Company shall
commence on April 1, 2002 and shall continue through April 1, 2007,
unless such employment is sooner terminated or subsequently extended as
hereinafter provided. The Company and the Executive may agree to extend the
period during which this agreement is in effect beyond the initial effective
period upon the terms and conditions of this Agreement or upon other terms, but
neither the Company nor the Executive is under any obligation to do so. The
period during which this Agreement is in effect shall constitute the "Employment
Period."

      4. Duties and Responsibilities.

            (a) Responsibilities. During the Employment Period, the Executive
shall perform his duties and responsibilities fully and faithfully as President
and Chief Scientific Officer, subject to the direction and supervision of the
Chief Executive Officer ("CEO") and the Board and the terms and conditions of
this Agreement. During such period, the Executive shall report solely to the CEO
and the Board. Executive shall have the duties and responsibilities customarily
assigned to the President and Chief Scientific Officer with such other duties
not
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inconsistent therewith as may from time to time be assigned to the Executive
by the CEO or the Board, and all employees of the Company who are involved in
research and development shall report to the Executive, subject to the Board's
ultimate control. During the Employment Period, the Executive shall perform all
services and acts necessary or advisable to fulfill the duties and
responsibilities that are commensurate and consistent with the Executive's
position. Executive agrees he shall devote substantially his full business time
and attention to, and exert his best efforts in, the performance of his duties
hereunder, so as to promote the business and best interests of the Company and
to comply with the Company's policies as in effect from time to time.
Notwithstanding the foregoing, Executive may engage in ordinary and customary
interactions with the scientific and academic communities, including writing and
reviewing articles and grants, editing books and attending conferences.

            (b) Exclusivity. Executive shall devote substantially his full time
to his duties hereunder and agrees that, during the Employment Period, except as
otherwise provided in Section 4(a), the Executive shall not provide consulting
services to, or become an employee of, any other firm, company, corporation, or
person engaged in a business.

            (c) Location. The Executive's principal place of business shall be
in Cambridge, Massachusetts, within thirty (30) miles there from ("Cambridge
Area") or within ten miles east of Worcester, MA, although travel could be part
of Executive's responsibilities. Executive shall perform services for the
Company in the Cambridge Area and at such other locations where Executive's
services might be required to be performed from time to time. Notwithstanding
the preceding sentence, Executive shall not be required to perform services at a
location other than the Cambridge Area for a period in excess of thirty (30)
consecutive days without the Executive's prior written consent, except in the
event of a change in location of the headquarters of the Company to a site
within the continental United States following a Change of Control.

      5. Compensation.  For all services rendered by Executive pursuant to this
Agreement, the Company shall pay Executive, and Executive agrees to accept, the
salary, stock options, bonuses, and other benefits described below in this
Section 5.

            (a) Base Salary. During the Employment Period, the Company shall pay
Executive an annual base salary of $ 360,000.00 ("Base Salary") and such Base
Salary shall be payable at periodic intervals in accordance with the Company's
payroll practices for salaried employees. In accordance with Section 5(c),
below, the amount of Base Salary shall be reviewed and approved, if applicable,
by the Board on at least an annual basis, and any increases in the amount of
Base Salary

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shall be effective as of the date determined by the Board. Executive's Base
Salary may be increased for any reason, including to reflect inflation or such
other adjustments as the Board may deem appropriate; provided, however, that
Executive's Base Salary, as in effect on the date hereof or as increased in
accordance with the terms of this Agreement, may not be subsequently decreased,
except with the prior written consent of the Executive.

            (b) Bonus. In addition to Base Salary and stock options, and to the
extent a bonus program is established by the Board, the Executive shall receive,
for each fiscal year of the Company ending with or within the Employment Period,
an annual bonus ("Bonus") whether pursuant to a formal bonus or incentive plan
or program of the Company or otherwise. Subject to this Section 5(b) and Section
5(c), below, such Bonus shall be based on criteria determined by the Board, in
its discretion. Any Bonus earned by the Executive for service or performance
rendered in any fiscal year within the Employment Period shall be paid to the
Executive in accordance with the applicable plan or program and the Company's
policies governing such matters. In the event of Executive's termination of
employment because of the Executive's death or Disability during the Employment
Period, the Company shall pay to Executive or Executive's estate, as applicable,
the pro rata portion of the Bonus that Executive would have earned in respect of
the portion of the year preceding Executive's death or commencement of
Disability.

            (c)   Annual Compensation Review.  Executive's compensation,
consisting of salary, stock option grants and bonuses, shall be reviewed
annually by the Board.

            (d) Medical, Dental and Other Healthcare Benefits. During the
Employment Period, Executive shall be eligible to participate in and receive
benefits under the Company's medical, dental, or other healthcare plans, as in
effect from time to time, that are available to officers or employees of the
Company.

            (e) Retirement Plan Benefits. Executive shall be entitled to
participate in the Company's tax-qualified and nonqualified retirement plans, as
in effect from time to time, that are available to officers and employees of the
Company and shall be entitled to receive the benefit of contributions to be
made, if any, by the Company for the benefit of Executive under the terms of the
applicable tax-qualified or nonqualified retirement plan.

            (f) Incentive Plans. During the Employment Period, Executive shall
be eligible to receive all benefits, including those under equity participation
or bonus programs, to which key employees are or

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become eligible under such plans or programs as may be established by the
Company from time to time.

            (g) Other Benefits. During the Employment Period, Executive shall be
entitled to participate in the benefit and fringe benefit programs afforded by
the Company to its executives from time to time; provided, however, that the
Company shall be required to pay or contribute to such programs in respect of
Executive for any calendar year of the Company an amount (the "Benefits Amount")
equal to the lesser of (i) 20% of Executive's annual base salary for such
calendar year or (ii) $50,000. The Benefits Amount shall not include
contributions made by the Company to FICA or FUTA or similar legally required
payments, expense reimbursements, vacation or any equity incentives granted to
Executive. If the Company, after providing a reasonably comprehensive benefit
and fringe benefit program for Executive, fails to spend for a calendar year the
entire Benefits Amount for such calendar year, the entire unspent Benefits
Amount shall be paid to Executive in cash within 60 days after the end of such
calendar year. Executive shall be entitled to paid vacation in accordance with
the Company's standard vacation policies in effect from time to time (such
policies as in effect on the date hereof providing that Executive is entitled to
six weeks paid vacation per calendar year based on his years of service to
date).

      6. [INTENTIONALLY LEFT BLANK]

      7. Termination of Employment.  The remedies described in this Section 7
are the exclusive remedies of the parties in connection with the termination of
Executive's employment under this Agreement

            (a) If the Executive's employment with the Company terminates for
any reason, except in connection with a Change of Control as provided for in
Section 7(b), below, then the Executive or his beneficiary, as applicable, shall
be entitled to receive the following severance benefits:

                  (i) Death. In the event Executive's employment hereunder is
terminated by reason of Executive's death, the Company shall pay Executive's
designated beneficiary or beneficiaries any Accrued Obligations; provided that
such amount shall be paid in a lump sum cash payment within thirty (30) days
after the Company's receipt of notification of Executive's death. Additionally,
any stock options previously granted to the Executive by the Company and held by
the Executive on the date of his death shall vest as of such date to the extent
such options would have vested (had Executive's employment not been terminated)
during the portion of the Employment Period that ends on the last day of the
twenty fourth (24th) month following the date on which Executive's death
occurred, and notwithstanding any provisions to the

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contrary contained in the stock option agreements, Executive shall be permitted
to exercise such stock options until the two year anniversary of death.

                  (ii) Disability. If Executive is unable to perform
substantially all of his duties hereunder due to a Disability and the Executive
does not return to the full-time performance of the Executive's duties within
thirty (30) days after written notice to return from the Company, the
Executive's employment under this Agreement may be terminated by the Company for
Disability. Such termination shall be effective on the 30th day following the
written notice or such later date as may be specified in the notice (the
"Disability Termination Date"). If Executive's employment hereunder is
terminated due to Disability, the Company shall pay Executive any Accrued
Obligations (such payment to be made within thirty (30) days after the
Disability Termination Date in the form of a lump sum cash payment).
Additionally, any stock options previously granted to the Executive by the
Company and held by the Executive on the Disability Termination Date shall vest
as of such date to the extent such options would have vested (had the
Executive's employment not been terminated) during that portion of the
Employment Period that ends on the last day of the twenty fourth (24th) month
following such date, and notwithstanding any provisions to the contrary
contained in the stock option agreements, Executive shall be permitted to
exercise such stock options until the two year anniversary of the Disability
Termination Date.

                  (iii) Termination by the Company for Cause. The Company may
terminate Executive's employment under this Agreement for Cause at any time. If
Executive's employment hereunder is terminated by the Company for Cause, the
Company shall pay Executive any Accrued Obligations, provided that such amount
shall be paid in a lump sum cash payment within thirty (30) days after such
termination date. Executive shall remain subject to the provisions of this
Agreement that, by their terms, survive the termination of the Executive's
employment with the Company. All options which are unvested on the date of
termination shall expire and terminate on that date and, notwithstanding any
provisions to the contrary contained in the stock option agreements, Executive
shall be permitted to exercise any vested stock options until the one year
anniversary of such termination date. All vested options which remain
unexercised after the one year anniversary of such termination date shall expire
and terminate.

                  (iv) Termination by the Company Other than for Death,
Disability or Cause. The Company may, at its option and with thirty (30) days'
written notice, terminate the Executive's employment under this Agreement
without Cause at any time. If the Executive's

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employment is terminated by the Company other than on account of Executive's
death, Disability, or for Cause, then, the Company shall pay Executive (A) the
lesser of (I) Executive's Base Salary for the twenty-four (24) consecutive
calendar months following the termination of Executive's employment (such
payments to be made under the Company's payroll practices applicable to salaried
executives) and (II) an amount equal to Executive's Base Salary for the period
from the time of termination until April 1, 2007, and (B) any Accrued
Obligations (such payment to be made within thirty (30) days after Executive's
termination date in the form of a lump sum cash payment). Additionally, any
stock options previously granted to the Executive by the Company and held by the
Executive on the date of termination shall vest as of such date to the extent
such option would have vested during the following thirty-six months (or portion
thereof) remaining in the Employment Period had Executive's employment not been
terminated, and notwithstanding any provisions to the contrary contained in the
stock option agreements, Executive shall be permitted to exercise such stock
options until the two year anniversary of such date. For this purpose,
Executive's Base Salary shall be his Base Salary in effect immediately before
his employment terminated and the Employment Period shall be the Employment
Period in effect immediately before his termination date.

                  (v) Termination by the Executive for Good Reason. Executive
may, for Good Reason, terminate this Agreement upon thirty (30) days' written
notice to the Company. If the Executive's employment is terminated by the
Executive for Good Reason, then the Company shall pay the Executive (A) the
lesser of (I) Executive's Base Salary for the twenty-four (24) consecutive
calendar months following the termination of Executive's employment (such
payments to be made under the Company's payroll practices applicable to salaried
executives) and (II) an amount equal to Executive's Base Salary for the period
from the time of termination until April 1, 2007, and (B) any Accrued
Obligations incurred through the date of such termination (such payment to be
made within thirty (30) days after such termination in the form of a lump sum
cash payment). Additionally, any stock options previously granted to the
Executive by the Company and held by the Executive on the date of termination
shall vest as of such date to the extent such option would have vested during
the following thirty-six months (or portion thereof) remaining in the Employment
Period had Executive's employment not been terminated, and notwithstanding any
provisions to the contrary contained in the stock option agreements, Executive
shall be permitted to exercise such stock options until the two year anniversary
of such date. For this purpose, Executive's Base Salary shall be his Base Salary
in effect immediately before his employment terminated and the Employment Period
shall be the Employment Period in effect immediately before his termination
date.

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                  (vi) Voluntary Termination by the Executive. Executive may,
without Good Reason, terminate this Agreement upon thirty (30) days' written
notice to the Company. If the Executive's employment is terminated by the
Executive without Good Reason, the Company shall pay Executive any Accrued
Obligations, provided that such amount shall be paid in a lump sum cash payment
within thirty (30) days after such termination date. All options which remain
unvested on the termination date shall expire and terminate as of that date and,
and notwithstanding any provisions to the contrary contained in the stock option
agreements, Executive shall be permitted to exercise all vested stock options
until the one year anniversary of such termination date. All vested options
which remain unexercised after the one year anniversary of such termination date
shall expire and terminate.

                  (vii) Continuation of Coverage.

                        (A)    If Executive's employment with the Company is
terminated under circumstances to which the provisions of Section 7(a)(iv),
Section 7(a)(v), Section 7(b)(iii) or Section 7(b)(vi) apply, the Company shall,
for the period during which the Company continues to pay Executive an amount
equal to his Base Salary and at its sole cost and expense, provide Executive and
his eligible dependents (if any) with healthcare, disability, and life insurance
benefits substantially similar to those benefits the Executive and his eligible
dependents (if any) were receiving immediately prior to the Executive's
termination of employment; provided, however,

                              (1)   the Company shall not be required to provide
medical coverage to the extent another employer provides comparable coverage,

                              (2)   with respect to death and disability
coverage, the Company shall not be required to provide coverage to the extent
another employer provides comparable coverage; and shall pay the cost of
supplemental coverage if a new employer provides less than comparable coverage,
to allow the Executive to purchase coverage to make total coverage comparable,
and

                              (3)   that the coverage provided by the Company
pursuant to this subsection 7(a)(vii)(A) shall be in lieu of any other continued
coverage for which the Executive or his dependents, if any, would otherwise be
eligible pursuant to COBRA.

                        (B)   If the Executive's employment with the Company is
terminated under circumstances to which the provisions of Section 7(a)(iv),
Section 7(a)(v), Section 7(b)(ii), Section 7(b)(iii) and

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Section 7(b)(vi) do not apply, Executive (and his dependents, if any) shall be
permitted to continue to participate in the Company's benefit plans, programs,
or arrangements to the extent the Company is required by law, including Part 6
of Title I of the Employee Retirement Income Security Act of 1974, as amended
("COBRA"), to offer such coverage.

                  (viii)      No Offset.  Any compensation derived by the
Executive from any subsequent employment or self-employment shall not be offset
against or reduce any amounts to which the Executive is entitled under this
Agreement.

            (b) Termination After a Change of Control. If Executive's employment
with the Company is terminated after the effective date of a Change of Control,
Executive shall be entitled to receive severance benefits as follows:

                  (i) Parachute Payments. If all or any portion of the amounts
payable to the Executive under this Agreement or otherwise are subject to the
excise tax imposed by Section 4999 of the Internal Revenue Code of 1986, as
amended ("Code") or a similar state tax or assessment, the Company shall pay to
the Executive an amount necessary to place the Executive in the same after-tax
position as Executive would have been had no such excise tax or assessment been
imposed. The amount payable pursuant to the preceding sentence shall be
increased to the extent necessary to pay income and excise taxes on such amount.
The determination of any amounts payable under this Section 7(b)(i) shall be
made by an independent accounting firm employed by the Company and such
determination shall be final, binding and conclusion on the parties hereto.

                  (ii) Voluntary Resignation. If Executive's employment with the
Company is terminated by the Executive by reason of his voluntary resignation
within thirty (30) days after the anniversary date of the effective date of a
Change in Control, the Company shall pay or otherwise provide to the Executive
the following severance benefits:

                        (A)   a lump sum cash payment in an amount equal to the
lesser of two (2) times the Executive's current Base Salary at the time of
termination, or the Executive's current Base Salary at the time of termination
multiplied by the aggregate number of years (or any portion thereof, calculated
on a daily basis) remaining in the Employment Period had the Executive's
employment not been terminated, provided that such amount shall be paid to the
Executive within ten (10) days after the date of termination;

                        (B)   until the earlier of the date the Employment
Period would otherwise have terminated had Executive's employment not

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been terminated, or the expiration of the twenty-four (24) month period measured
from the date of the Executive's termination of employment, the Company shall,
at its sole cost and expense provide Executive and his eligible dependents (if
any) with healthcare, disability, and life insurance benefits substantially
similar to those benefits the Executive and his eligible dependents (if any)
were receiving immediately prior to the Executive's termination of employment;
provided, however,

                              (1)   the Company shall not be required to provide
medical coverage to the extent another employer provides comparable coverage,

                              (2)   with respect to death and disability
coverage, the Company shall not be required to provide coverage to the extent
another employer provides comparable coverage; and shall pay the cost of
supplemental coverage if a new employer provides less than comparable coverage,
to allow the Executive to purchase coverage to make total coverage comparable,
and

                              (3)   that the coverage provided by the Company
pursuant to this subsection 7(b)(ii)(B) shall be in lieu of any other continued
coverage for which the Executive or his dependents, if any, would otherwise be
eligible pursuant to COBRA; and

                        (C)   notwithstanding any provisions to the contrary
contained in the stock option agreements, Executive shall be permitted to
exercise all vested stock options until the one year anniversary of the date of
the Executive's termination of employment.

                  (iii) Termination by the Executive for Good Reason. If, after
the effective date of a Change of Control, Executive terminates his employment
with the Company for Good Reason, the Company shall pay or otherwise provide to
the Executive the severance benefits described in Section 7(a)(v) hereof.

                  (iv) Termination by Reason of Death. If, after the effective
date of a Change of Control, Executive's employment with the Company is
terminated by reason of Executive's death, the Company shall pay or otherwise
provide to Executive's designated beneficiary or beneficiaries the severance
benefits described in Section 7(a)(i) hereof.

                  (v) Termination by Reason of Disability. If, after the
effective date of a Change of Control, Executive's employment with the Company
is terminated by the Company by reason of Disability as described in Section
7(a)(ii) hereof, the Company shall pay or otherwise provide to Executive the
severance benefits described in that section.

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                  (vi) Termination by the Company Other Than for Death,
Disability or Cause. If, after the effective date of a Change of Control,
Executive's employment with the Company is terminated by the Company other than
for Death, Disability, or Cause, the Company shall pay or otherwise provide to
the Executive the severance benefits described in Section 7(a)(iv) hereof.

                  (vii) Termination by the Company for Cause. If, after the
effective date of a Change of Control, Executive's employment with the Company
is terminated by the Company for Cause, the Company shall pay Executive the
amounts described in Section 7(a)(iii) hereof.

                  (viii) Voluntary Termination by Executive. If, after the
effective date of a Change of Control, Executive voluntarily terminates his
employment with the Company under circumstances to which section 7(b) (ii) does
not apply, the Company shall pay Executive the amounts described in Section
7(a)(vi).

                  Acceleration of Vesting. Any provisions of this Agreement
regarding vesting of stock options notwithstanding, the vesting of all
Previously Granted Stock Options shall be accelerated as described below upon
the occurrence of the following events:

                         Creeping Tender.  In the event of a Creeping Tender,
the unvested portion of the Previously Granted Stock Options shall become fully
vested and nonforfeitable as of the date that is ten business days before the
effective date of the Creeping Tender.

                         Acquisition Event.  Upon the execution by the Company
of an agreement to effect an Acquisition Event that is not a Creeping Tender,
the unvested portion of the Previously Granted Stock Options shall become fully
vested and nonforfeitable upon the occurrence of the Acquisition Event or as of
such earlier date as may be specified by the Board by written notice to the
Executive and the Board may take one or both of the following actions with
respect to the Previously Granted Stock Options: (I) provide that the Previously
Granted Stock Options shall be assumed, or equivalent stock options be
substituted by the acquiring or succeeding corporation (or an affiliate
thereof), or (II) upon written notice to the Executive, provide that all then
unexercised Previously Granted Stock Options will terminate to the extent not
exercised by the Executive prior to the consummation of such Acquisition Event
or such earlier date as may be specified by the Board by written notice to the
Executive.

                        IP Divestiture.  Upon an IP Divestiture, the option to
purchase shares of the Company's common stock at $0.825 per

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share granted to Executive on July 25, 2001 shall immediately vest with respect
to 500,000 shares.

                  (ix) Amendments to Stock Option Agreements. The Company and
the Executive agree promptly to take such steps to amend the Previously Granted
Stock Options to the extent necessary to reflect the provisions of this Section
7.

      8. Proprietary Information; Company Documents and Materials.

            (a) Proprietary Information. Executive acknowledges that during the
Employment Period, Executive will occupy a position of trust and confidence with
respect to Proprietary Information of the Company. Executive understands that he
possesses or will possess Proprietary Information that is important to the
Company's business and operation. Executive acknowledges that such Proprietary
Information is specialized, unique in nature and of great value to the Company
and its Affiliates, and that such information gives the Company and its
Affiliates a competitive advantage. Executive acknowledges that all Proprietary
Information is and shall remain the sole property of the Company or any of its
Affiliates. Executive shall not disclose to others or use, whether directly or
indirectly, any Proprietary Information, or anything relating to such
information, regarding the Company or any of its Affiliates; provided, however
that Executive's obligations under this Section 8 shall not apply to any
information that (i) is or becomes known to the general public under
circumstances involving no breach by Executive of the terms of this Section 8,
(ii) is generally disclosed to third parties by the Company without restriction
on such third parties, (iii) is approved for release by written authorization of
the Board of Directors or an authorized employee of the Company, (iv) is
communicated to Executive by a third party under no duty of confidentiality with
respect to such information to the Company or another party, or (v) is required
to be disclosed by Executive to comply with applicable laws, governmental
regulations, or court order, provided that Executive provides prior written
notice of such disclosure to the Company and an opportunity for the Company to
object to such disclosure and further provided that Executive cooperates with
the Company and takes reasonable and lawful actions requested by the Company
(the out-of-pocket costs of which shall be paid by the Company) to avoid and/or
minimize the extent of such disclosure.

            (b) Company Documents and Materials. Executive agrees that during
Executive's employment by the Company, Executive will not remove any Company
documents or materials, including Proprietary Information, from the business
premises of the Company or deliver any such Company documents or materials to
any person or entity outside the Company, except as Executive is required to do
in connection with

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performing the duties of Executive's employment. Executive agrees that,
immediately upon the termination of Executive's employment by Executive or by
the Company for any reason, or during Executive's employment if so requested by
the Company, Executive will return all Company documents and materials, computer
tapes and disks, records, lists, data, drawings, prints, notes and written
information, apparatus, equipment and other physical property, or any
reproduction of such property, excepting only (i) Executive's personal copies of
records relating to Executive's compensation; (ii) Executive's personal copies
of any materials previously distributed generally to stockholders of the
Company; and (iii) Executive's copy of this Agreement. Provided that the Company
has copies and the matters covered therein do not contain Proprietary
Information, Executive may keep copies of correspondence or publications
relating to scientific or academic matters.

      9. Non-solicitation and Non-competition.

            (a) Non-solicitation. Executive agrees that during his employment
with the Company and for a period of one (1) year following the termination of
his employment with the Company, the Executive shall not hire, attempt to hire,
or assist in or facilitate in any way the hiring of any person who, at the time
of any such action by the Executive, is an employee of the Company (or any of
its Affiliates).

            (b) Non-competition. Executive agrees that if his employment with
the Company is terminated for any reason, including upon the expiration of the
Employment Period, for a period of one (1) year from the date of such
termination of employment, the Executive shall not, directly or indirectly, own,
manage, operate, control, be employed by, participate in, or be connected in any
manner with the ownership, management, operation or control of any company, or
any subsidiary or division of a company, more than 50% of whose annual revenues,
annual research and development expense (including the cost of research and
laboratory personnel) or income is attributable to the business of developing,
marketing or selling antisense therapeutics or oligonucleotide-based
immunostimulatory/immunoregulatory therapeutics or oligonucleotide-based
diagnostics.

      10. Assignment of Rights. All inventions, discoveries, computer programs,
data, technology, designs, innovations and improvements (whether or not
patentable and whether or not copyrightable) related to the business of the
Company which are made, conceived, reduced to practice, created, written,
designed or developed by the Executive, solely or jointly with others and
whether during normal business hours or otherwise, during his employment by the
Company pursuant to this Agreement ("Inventions") shall be the sole property of
the Company. The Executive hereby assigns to the Company all such Inventions and
any

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and all related patents, copyrights, trademarks, trade names, and other
industrial and intellectual property rights and applications therefor, in the
United States and elsewhere and appoints any officer of the Company as his duly
authorized attorney, but without any out-of-pocket expenses to the Executive, to
executive, file, prosecute and protect the same before any government agency,
court or authority. The Executive hereby waives all claims to moral rights in
any Invention. Upon the request of the Company and at the Company's expense, the
Executive shall execute such further assignments, documents and other
instruments as may be necessary or desirable to fully and completely assign all
such Inventions to the Company and to assist the Company in applying for,
obtaining and enforcing patents or copyrights or other rights in the United
States and in any foreign county with respect to any such Invention. The
Executive shall promptly disclose to the Company all such Inventions and will
maintain adequate and current written records (in the form of notes, sketches,
drawings and as may be reasonably specified by the Company) to document the
conception and/or first actual reduction to practice of any such Invention. Such
written records shall be available to and remain the sole property of the
Company at all times. Executive shall, upon the Company's request, whether
during or after the Employment Period, promptly execute and deliver to the
Company all such assignments, certificates and instruments, and shall promptly
perform such other acts, as the Company may from time to time in its discretion
deem necessary or desirable to evidence, establish, maintain, perfect, enforce
or defend the Company's rights in the inventions. These services (the "IP
Services"), shall be rendered by the Executive without additional compensation
during the Employment Period, the Compliance Period (as defined below) and at
any time when the Company is paying the Executive his Base Salary pursuant to
Sections 7(a)((iv), 7(a)(v), 7(b)((iii) or 7(b)(vi) (payments made pursuant to
such sections, the "Severance Payments"). The Executive shall otherwise render
the IP Services at the rate of compensation provided in the last sentence of
this paragraph. Upon termination of the Executive's employment, whether pursuant
to the termination of this Agreement upon completion of its five-year term or
otherwise, the Company shall be obligated to pay Executive the sum of $30,000
per month for a period (the "Compliance Period"), equal to twelve months minus
the number of months, if any, during which the Company makes Severance Payments
to the Executive, but only for as long as the Executive complies with the
reasonable requests which the Company may make for IP Services. The Compliance
Period shall begin after all Severance Payments, if any, have been made. In
addition, the Executive agrees, from time to time, and for as long as reasonably
required, to make himself available on a consulting basis to assist the Company
in the prosecution of patent applications or other filings or proceedings before
the Office of Patents and Trademarks and to advise with respect to issues
arising in the licensing of the Company's

                                      -13-
<PAGE>
patents and the pursuit or defense of infringement claims. The Company's
requests under the preceding sentence shall be made upon reasonable notice to
Executive and the Company shall pay the Executive for such services at the
hourly rate of $200 per hour plus reasonable expenses.

      11. Publications. Following the expiration or termination of the
Employment Period, Executive will have a continuing right, on the terms and
conditions set forth in this Section 11, to disclose in scientific journals or
publications or in presentations at scientific conferences the results of any
research performed by Executive while employed by the Company. Executive will
provide the Company with an advance copy of any proposed publication or
presentation before submission of such advance copy to any publisher or before
the intended date of presentation, as the case may be. If the Company informs
Executive, within 30 days of receipt of such advance copy, that such publication
or presentation would have an adverse effect on the confidentiality of any
confidential information of the Company or on the ability of the Company to
obtain, enforce or maintain any intellectual property rights in any proprietary
information of the Company, Executive will delay or prevent such publication or
presentation as proposed. Executive will incorporate in such proposed
publication or presentation prior to its submission such changes, including
without limitation deletions, as the Company believes are necessary to preserve
the confidentiality of any confidential information, and Executive will delay
such proposed publication or presentation until such time as the Company has
filed a U.S. patent application covering any proprietary information.

      12. Successors. Any successor to the Company (whether direct or indirect
and whether by purchase, lease, merger, consolidation, liquidation or otherwise)
or to all or substantially all of the Company's business and/or assets shall
assume the obligations under this Agreement and shall perform the obligations
under this Agreement in the same manner and to the same extent as the Company
would be required to perform such obligations in the absence of a succession.
The Company may assign this Agreement without the Executive's consent to any
company that acquires all or substantially all of the Company's stock or assets.
Executive may not assign this Agreement and no person other than the Executive
(or his estate) may assert the Executive's rights under this Agreement.

      13. Notice. All notices, requests, consents and other communications
hereunder ("Notices") to any party shall be contained in a written instrument
addressed to such party at the address set forth below or such other address as
may hereafter be designated in writing by the addressee to the addressor listing
all parties and shall be deemed

                                      -14-
<PAGE>
given (a) when delivered in person or duly sent by fax showing confirmation of
receipt, (b) three days after being duly sent by first class mail postage
prepaid, or (c) two days after being duly sent by DHL, Federal Express or other
recognized express courier service:

            (a)   if to the Company, to:

            Hybridon, Inc.
            345 Vassar Street
            Cambridge, MA 02139
            fax: (617) 679-5582

            (b)   if to the Executive, to:

      14. Company Plans. Except to the extent otherwise explicitly provided by
this Agreement, any awards made to the Executive under any Company compensation
or benefit plan, program, or arrangement shall be governed by the terms of that
plan, program, or arrangement and any applicable award agreement thereunder, as
in effect from time to time. Notwithstanding the preceding sentence, Executive
shall not be entitled to participate in any Company compensation or benefit
plan, program or arrangement that is established after his employment with the
Company terminates, and except as specifically provided in this Agreement,
Executive shall not be entitled to any additional grants or awards under any
Company compensation or benefit plan, program, or arrangement after his
employment with the Company terminates.

      15.   Miscellaneous Provisions.

            (a) Entire Agreement. This Agreement constitutes the entire
agreement between the parties and terminates and supersedes any and all prior
agreements and understandings (whether written or oral) between the parties with
respect to the subject matter of this Agreement. Executive acknowledges and
agrees that neither the Company, nor anyone acting on its behalf has made, and
in executing this Agreement Executive has not relied upon, any representations,
promises, or inducements except to the extent the same is expressly set forth
herein.

            (b) Waiver. No provision of this Agreement shall be modified,
waived, or discharged unless the modification, waiver, or discharge is agreed to
in writing and signed by Executive and by an authorized officer or
representative of the Company (other than Executive). No waiver by either party
of any breach of, or of compliance with, any condition or provision of this
Agreement by the other party shall be considered a waiver of any other condition
or provision or of the same condition or provision at a preceding or subsequent
time.

                                      -15-
<PAGE>
            (c) Capacity. The Executive represents and warrants to the Company
that he is not now under any obligation, of a contractual nature or otherwise,
to any person, firm, corporation, association or other entity that is
inconsistent, or in conflict, with this Agreement or which would prevent, limit
or impair in any way the performance by Executive of his obligations hereunder.

            (d) Consulting. Executive and the Company may, but are not required
to, enter into an agreement pursuant to which Executive will provide consulting
services to the Company after the date of Executive's retirement or termination
of employment with the Company. Any consulting fees paid to the Executive will
be in addition to any retirement or severance payments the Executive is entitled
to receive from the Company or under any plans, programs, or arrangements
maintained by the Company.

            (e) Severability. In the event that a court of competent
jurisdiction determines that any portion of this Agreement is in violation of
any law or public policy, only the portion of this Agreement that violates such
law or public policy shall be stricken. All portions of this Agreement that do
not violate any statute or public policy shall continue in full force and
effect. Further, any court order striking any portion of this Agreement shall
modify the stricken terms as narrowly as possible to give effect to the
intentions of the parties to this Agreement, as expressed herein.

            (f) Survival of Provisions. The obligations contained in Sections 8,
9, 10 and 11 above shall survive the termination or expiration of the Employment
Period or this Agreement, as applicable, and shall be fully enforceable
thereafter in accordance with the terms of this Agreement.

            (g) Withholding. The Executive acknowledges that salary and all
other compensation payable under this Agreement shall be subject to withholding
for income and other applicable taxes to the extent required by law, as
determined by the Company in its sole discretion.

            (h) Headings. The headings or other captions contained in this
Agreement are for convenience of reference only and shall not be used in
interpreting, construing or enforcing any of the provisions of this Agreement.

            (i) Governing Law. This Agreement shall be governed by the laws of
the State of Massachusetts without giving effect to any conflict of law rules
that would require the application of the laws of any jurisdiction other than
the internal laws of the State of Massachusetts to

                                      -16-
<PAGE>
the rights and duties of the parties, except to the extent the laws of the State
of Massachusetts are preempted by federal law.

            (j) Terms. Where appropriate in this Agreement, words used in the
singular shall include the plural, and words used in the masculine shall include
the feminine or neuter.

            (k) Legal Fees. The Company shall pay or reimburse to the Executive
an amount equal to reasonable fees for legal representation incurred by the
Executive in connection with the preparation of this Agreement and the amendment
of existing options agreements in an amount not to exceed $6,000.

            (l) Counterparts. This Agreement may be executed in multiple
counterparts, each of which shall be deemed to be an original, and all of which
together shall constitute one agreement binding on the parties hereto.

                                      -17-
<PAGE>
      IN WITNESS WHEREOF, the parties hereto have executed this Agreement
effective as of the date first mentioned above.

HYBRIDON, INC.                      EXECUTIVE

BY:   /s/ James B. Wyngaarden       BY:   /s/ Sudhir Agrawal
      -----------------------             ---------------------------------
                                          Sudhir Agrawal

TITLE: Chairman                     DATE: April 1, 2002
      -----------------------             ---------------------------------

DATE:  April 1, 2002
      -----------------------

                                      -18-
<PAGE>
                                   APPENDIX A

                                   DEFINITIONS

      ACCRUED OBLIGATIONS. "Accrued Obligations" shall mean the sum of (i) any
portion of Executive's Bonus accrued as of the date of termination of the
Executive's employment for any reason, including by reason of his death, which
has not yet been paid, and (ii) reimbursement of any reimbursable expense
incurred by the Executive through the date of termination of employment.

      ACQUISITION EVENT means

                  (i) any merger or consolidation which results in the voting
securities of the Company outstanding immediately prior thereto representing
(either by remaining outstanding or by being converted into voting securities of
the surviving or acquiring entity) less than 60% of the combined voting power of
the voting securities of the Company or such surviving or acquiring entity
outstanding immediately after such merger or consolidation;

                  (ii)  any sale of all or substantially all of the assets of
the Company;

                  (iii) the complete liquidation of the Company; or

                  (iv) the acquisition of "beneficial ownership" (as defined in
Rule 13d-3 under the Exchange Act) of securities of the Company representing 50%
or more of the combined voting power of the Company's then outstanding
securities (other than through a merger or consolidation or an acquisition of
securities directly from the Company) by any "person," as such term is used in
Sections 13(d) and 14(d) of the Exchange Act, other than the Company, any
trustee or other fiduciary holding securities under an employee benefit plan of
the Company or any corporation owned directly or indirectly by the stockholders
of the Company in substantially the same proportion as their ownership of stock
of the Company (an event specified in this clause (iv) being referred to as a
"Creeping Tender").

      AFFILIATE. "Affiliate" shall mean any person or entity which directly or
indirectly controls, is controlled by or is under common control with the
Company, including any entity directly or indirectly controlled by the Company
through the Company's ownership of fifty percent (50%) or more of the voting
interests of such entity.

      CAUSE. "Cause" shall mean Executive's (i) material breach of any material
terms of the Agreement, (ii) plea of guilty or nolo contendre to, or

                                      -19-
<PAGE>
conviction of, the commission of a felony offense, (iii) repeated unexplained or
unjustified absence, or refusals to carry out the lawful directions of the Board
or (iv) material breach of a fiduciary duty owed to the Company under this
Agreement, provided that any action or inaction described by (i), (iii) or (iv),
above, shall not be the basis of a termination of the Executive's employment
with the Company for "Cause" unless the Company provided the Executive with at
least twenty (20) days advance written notice specifying in reasonable detail
the conduct in need of being cured and such conduct was not cured within the
notice period.

      CHANGE OF CONTROL.  "Change of Control" shall mean the occurrence of any
of the following events:

      (i) a change in the composition of the Board over a period of thirty-six
(36) consecutive months or less such that a majority of the members of the Board
ceases to be comprised of individuals who are Continuing Members; for such
purpose, a "Continuing Member" shall mean an individual who is a member of the
Board on the date of this Agreement and any successor of a Continuing Member who
is elected to the Board or nominated for election by action of a majority of
Continuing Members then serving on the Board; or

      (ii)  the consummation of an Acquisition Event other than an IP
Divestiture.

      DISABILITY. "Disability" shall mean the inability of the Executive to
perform all the material duties of Executive's position for a continuous period
of at least ninety (90) days due to a permanent physical or mental impairment,
as determined and certified by a physician selected by the Executive and with
the concurrence of a physician selected by the Company, provided that if the
physician selected by the Executive and the physician selected by the Company do
not agree regarding the determination and certification, a determination and
certification rendered by an independent physician mutually agreed upon by the
Executive and the Company shall be final and binding on the parties with respect
to this Agreement.

      GOOD REASON. "Good Reason" shall mean the occurrence of one or more of the
following: (i) any action by the Company which results in a material diminution
of Executive's position, title, annual base salary, authority, duties or
responsibilities or reporting structure; (ii) any material breach of this
Agreement by the Company which is not remedied by the Company within thirty (30)
days after receipt by the Company of notice thereof given by Executive
specifying in reasonable detail the alleged breach; (iii) failure to elect
Executive to serve on the Board during the Employment Period; or (iv) relocation
of the Company's headquarters outside the Cambridge Area or 10 miles east of the

                                      -20-
<PAGE>
Worcester area, except in the event of a change in the location of the
headquarters of the Company to a site within the continental United States
following a Change of Control.

      IP DIVESTITURE. "IP Divestiture" shall mean a sale or licensing by the
Company of all or substantially all of its assets (including patents, patent
applications and know-how) relating to any one of its technology platforms.

      PROPRIETARY INFORMATION. "Proprietary Information" shall mean information
that was developed, created, or discovered by or on behalf of the Company, or
which became or will become known by, or was or is conveyed to the Company;
including, but not limited to, trade secrets, designs, technology, know-how,
processes, data, ideas, techniques, inventions (whether patentable or not),
works of authorship, formulae, business and development plans, client or
customer lists, software programs and subroutines, source and object code,
algorithms, terms of compensation and performance levels of Company employees,
information about the Company or any of its Affiliates, and their clients and
customers that is not disclosed by the Company or any of its Affiliates for
financial reporting purposes and that was learned by the Executive in the course
of employment by the Company or any of its Affiliates, other information
concerning the Company's actual or anticipated business, research or
development, or which is received in confidence by or for the Company from any
other person, and all papers, resumes, and records (including electronic or
computer-generated records) of the documents containing such Proprietary
Information. Proprietary Information shall not include information that is
publicly available or available through third party sources so long as it has
not become available through a breach of this Agreement by Executive.

      PREVIOUSLY GRANTED STOCK OPTIONS. "Previously Granted Stock Options" shall
mean options granted to Executive during the period commencing with his 1997
Employment Agreement.

                                      -21-<PAGE>
                                                                    Exhibit 10.2

                                 HYBRIDON, INC.

                              EMPLOYMENT AGREEMENT

      THIS EMPLOYMENT AGREEMENT ("Agreement") is entered into by and between
Robert G. Andersen ("Executive") and Hybridon, Inc., a Delaware corporation (the
"Company"), and is effective as of the 1st day of April, 2002.

      WHEREAS, the Company desires to establish its right to the services of
Executive, in the capacity described below, on the terms and conditions
hereinafter set forth, and Executive is willing to accept such employment on
such terms and conditions;

      NOW, THEREFORE, in consideration of the mutual agreements hereinafter set
forth, Executive and the Company have agreed and do hereby agree as follows:

      1. Definitions.  The capitalized terms in this Agreement shall have the
meanings set forth in this Agreement or Appendix A attached hereto.

      2. Engagement.  The Company hereby agrees to employ Executive as its Chief
Financial Officer and Vice President of Operations and the Executive hereby
accepts such employment on the terms and conditions hereinafter set forth.

      3. Employment Period. The Executive's employment with the Company under
terms of this Agreement shall commence on April 1, 2002 and shall continue
through April 1, 2006, unless such employment is sooner terminated or
subsequently extended as hereinafter provided. The Company and the Executive may
agree to extend the period during which this agreement is in effect beyond the
initial effective period upon the terms and conditions of this Agreement or upon
other terms, but neither the Company nor the Executive is under any obligation
to do so. The period during which this Agreement is in effect shall constitute
the "Employment Period."

      4. Duties and Responsibilities.

            (a) Responsibilities. During the Employment Period, the Executive
shall perform his duties and responsibilities fully and faithfully as Chief
Financial Officer, subject to the direction and supervision of the Chief
Executive Officer ("CEO") and the Board and the terms and conditions of this
Agreement. During such period, the Executive shall report solely to the CEO and
the Board. Executive shall be permitted to attend, as an observer, all Board
meetings except those in executive session. Executive shall have the duties and
responsibilities customarily
<PAGE>
assigned to the Chief Financial Officer and Vice President of Operations with
such other duties not inconsistent therewith as may from time to time be
assigned to the Executive by the CEO or the Board. Such duties shall include,
without limitation, the management of the Company's financial affairs,
operations and human resources, provided that the Board shall have discretion to
re-assign the human resources function. During the Employment Period, the
Executive shall perform all services and acts necessary or advisable to fulfill
the duties and responsibilities that are commensurate and consistent with the
Executive's position. Executive agrees he shall devote substantially his full
business time and attention to, and exert his best efforts in, the performance
of his duties hereunder, so as to promote the business and best interests of the
Company and to comply with the Company's policies as in effect from time to
time, provided, however, that Executive may serve, at the Board's pleasure, as a
director of Origenix, Inc. and other companies with the CEO's approval.

            (b) Exclusivity. Executive shall devote substantially his full time
to his duties hereunder and agrees that, during the Employment Period, except as
otherwise provided in Section 4(a), the Executive shall not provide consulting
services to, or become an employee of, any other firm, company, corporation, or
person engaged in a business.

            (c) Location. The Executive's principal place of business shall be
in Cambridge, Massachusetts, within thirty (30) miles there from ("Cambridge
Area") or within ten miles east of Worcester, MA, although travel could be part
of Executive's responsibilities. Executive shall perform services for the
Company in the Cambridge Area and at such other locations where Executive's
services might be required to be performed from time to time. Notwithstanding
the preceding sentence, Executive shall not be required to perform services at a
location other than the Cambridge Area for a period in excess of thirty (30)
consecutive days without the Executive's prior written consent, except in the
event of a change in location of the headquarters of the Company to a site
within the continental United States following a Change of Control.

      5. Compensation.  For all services rendered by Executive pursuant to this
Agreement, the Company shall pay Executive, and Executive agrees to accept, the
salary, stock options, bonuses, and other benefits described below in this
Section 5.

            (a) Base Salary. During the Employment Period, the Company shall pay
Executive an annual base salary of $258,000.00 ("Base Salary") and such Base
Salary shall be payable at periodic intervals in accordance with the Company's
payroll practices for salaried employees. In accordance with Section 5(c),
below, the amount of Base Salary shall be reviewed and approved, if applicable,
by the Board on at

                                      -2-
<PAGE>
least an annual basis, and any increases in the amount of Base Salary shall be
effective as of the date determined by the Board. Executive's Base Salary may be
increased for any reason, including to reflect inflation or such other
adjustments as the Board may deem appropriate; provided, however, that
Executive's Base Salary, as in effect on the date hereof or as increased in
accordance with the terms of this Agreement, may not be subsequently decreased,
except with the prior written consent of the Executive.

            (b) Bonus. In addition to Base Salary and stock options, and to the
extent a bonus program is established by the Board, the Executive shall receive,
for each fiscal year of the Company ending with or within the Employment Period,
an annual bonus ("Bonus") whether pursuant to a formal bonus or incentive plan
or program of the Company or otherwise. Subject to this Section 5(b) and Section
5(c), below, such Bonus shall be based on criteria determined by the Board, in
its discretion. Any Bonus earned by the Executive for service or performance
rendered in any fiscal year within the Employment Period shall be paid to the
Executive in accordance with the applicable plan or program and the Company's
policies governing such matters. In the event of Executive's termination of
employment because of the Executive's death or Disability during the Employment
Period, the Company shall pay to Executive or Executive's estate, as applicable,
the pro rata portion of the Bonus that Executive would have earned in respect of
the portion of the year preceding Executive's death or commencement of
Disability.

            (c)   Annual Compensation Review.  Executive's compensation,
consisting of salary, stock option grants and bonuses, shall be reviewed
annually by the Board.

            (d) Medical, Dental and Other Healthcare Benefits. During the
Employment Period, Executive shall be eligible to participate in and receive
benefits under the Company's medical, dental, or other healthcare plans, as in
effect from time to time, that are available to officers or employees of the
Company.

            (e) Retirement Plan Benefits. Executive shall be entitled to
participate in the Company's tax-qualified and nonqualified retirement plans, as
in effect from time to time, that are available to officers and employees of the
Company and shall be entitled to receive the benefit of contributions to be
made, if any, by the Company for the benefit of Executive under the terms of the
applicable tax-qualified or nonqualified retirement plan.

            (f) Incentive Plans. During the Employment Period, Executive shall
be eligible to receive all benefits, including those under

                                      -3-
<PAGE>
equity participation or bonus programs, to which key employees are or become
eligible under such plans or programs as may be established by the Company from
time to time.

            (g) Vacation. Executive shall be entitled to paid vacation in
accordance with the Company's standard vacation policies in effect from time to
time.

      6. [INTENTIONALLY LEFT BLANK]

      7. Termination of Employment.  The remedies described in this Section 7
are the exclusive remedies of the parties in connection with the termination of
Executive's employment under this Agreement

            (a) If the Executive's employment with the Company terminates for
any reason, except in connection with a Change of Control as provided for in
Section 7(b), below, then the Executive or his beneficiary, as applicable, shall
be entitled to receive the following severance benefits:

                  (i) Death. In the event Executive's employment hereunder is
terminated by reason of Executive's death, the Company shall pay Executive's
designated beneficiary or beneficiaries any Accrued Obligations; provided that
such amount shall be paid in a lump sum cash payment within thirty (30) days
after the Company's receipt of notification of Executive's death. Additionally,
any stock options previously granted to the Executive by the Company and held by
the Executive on the date of his death shall vest as of such date to the extent
such options would have vested (had Executive's employment not been terminated)
during the portion of the Employment Period that ends on the last day of the
twelfth (12th) month following the date on which Executive's death occurred, and
notwithstanding any provisions to the contrary contained in the stock option
agreements, Executive shall be permitted to exercise such stock options until
the two year anniversary of death.

                  (ii) Disability. If Executive is unable to perform
substantially all of his duties hereunder due to a Disability and the Executive
does not return to the full-time performance of the Executive's duties within
thirty (30) days after written notice to return from the Company, the
Executive's employment under this Agreement may be terminated by the Company for
Disability. Such termination shall be effective on the 30th day following the
written notice or such later date as may be specified in the notice (the
"Disability Termination Date"). If Executive's employment hereunder is
terminated due to Disability, the Company shall pay Executive any Accrued
Obligations (such payment to be made within thirty (30) days after the
Disability Termination Date in

                                      -4-
<PAGE>
the form of a lump sum cash payment). Additionally, any stock options previously
granted to the Executive by the Company and held by the Executive on the
Disability Termination Date shall vest as of such date to the extent such
options would have vested (had the Executive's employment not been terminated)
during that portion of the Employment Period that ends on the last day of the
twelfth (12th) month following such date, and notwithstanding any provisions to
the contrary contained in the stock option agreements, Executive shall be
permitted to exercise such stock options until the two year anniversary of the
Disability Termination Date.

                  (iii) Termination by the Company for Cause. The Company may
terminate Executive's employment under this Agreement for Cause at any time. If
Executive's employment hereunder is terminated by the Company for Cause, the
Company shall pay Executive any Accrued Obligations, provided that such amount
shall be paid in a lump sum cash payment within thirty (30) days after such
termination date. Executive shall remain subject to the provisions of this
Agreement that, by their terms, survive the termination of the Executive's
employment with the Company. All options which are unvested on the date of
termination shall expire and terminate on that date and, notwithstanding any
provisions to the contrary contained in the stock option agreements, Executive
shall be permitted to exercise any vested stock options until the one year
anniversary of such termination date. All vested options which remain
unexercised after the one year anniversary of such termination date shall expire
and terminate.

                  (iv) Termination by the Company Other than for Death,
Disability or Cause. The Company may, at its option and with thirty (30) days'
written notice, terminate the Executive's employment under this Agreement
without Cause at any time. If the Executive's employment is terminated by the
Company other than on account of Executive's death, Disability, or for Cause,
then the Company shall pay the Executive (A) the lesser of (I) Executive's Base
Salary for the twenty-four (24) consecutive calendar months following the
termination of Executive's employment (such payments to be made under the
Company's payroll practices applicable to salaried executives) and (II) an
amount equal to Executive's Base Salary for the period from the time of
termination until April 1, 2006, but in no event less than twelve (12) calendar
months, and (B) any Accrued Obligations incurred through the date of such
termination (such payment to be made within thirty (30) days after such
termination in the form of a lump sum cash payment). Additionally, any stock
options previously granted to the Executive by the Company and held by the
Executive on the date of termination shall vest as of such date to the extent
such option would have vested during the following thirty-six months (or portion
thereof) remaining in the

                                      -5-
<PAGE>
Employment Period had Executive's employment not been terminated, and
notwithstanding any provisions to the contrary contained in the stock option
agreements, Executive shall be permitted to exercise such stock options until
the two year anniversary of such date. For this purpose, Executive's Base Salary
shall be his Base Salary in effect immediately before his employment terminated
and the Employment Period shall be the Employment Period in effect immediately
before his termination date.

                  (v) Termination by the Executive for Good Reason. Executive
may, for Good Reason, terminate this Agreement upon thirty (30) days' written
notice to the Company. If the Executive's employment is terminated by the
Executive for Good Reason, then the Company shall pay the Executive (A) the
lesser of (I) Executive's Base Salary for the twenty-four (24) consecutive
calendar months following the termination of Executive's employment (such
payments to be made under the Company's payroll practices applicable to salaried
executives) and (II) an amount equal to Executive's Base Salary for the period
from the time of termination until April 1, 2006, but in no event less than
twelve (12) calendar months, and (B) any Accrued Obligations incurred through
the date of such termination (such payment to be made within thirty (30) days
after such termination in the form of a lump sum cash payment). Additionally,
any stock options previously granted to the Executive by the Company and held by
the Executive on the date of termination shall vest as of such date to the
extent such option would have vested during the following thirty-six months (or
portion thereof) remaining in the Employment Period had Executive's employment
not been terminated, and notwithstanding any provisions to the contrary
contained in the stock option agreements, Executive shall be permitted to
exercise such stock options until the two year anniversary of such date. For
this purpose, Executive's Base Salary shall be his Base Salary in effect
immediately before his employment terminated and the Employment Period shall be
the Employment Period in effect immediately before his termination date.

                  (vi) Voluntary Termination by the Executive. Executive may,
without Good Reason, terminate this Agreement upon thirty (30) days' written
notice to the Company. If the Executive's employment is terminated by the
Executive without Good Reason, the Company shall pay Executive any Accrued
Obligations, provided that such amount shall be paid in a lump sum cash payment
within thirty (30) days after such termination date. All options which remain
unvested on the termination date shall expire and terminate as of that date and,
and notwithstanding any provisions to the contrary contained in the stock option
agreements, Executive shall be permitted to exercise all vested stock options
until the one year anniversary of such

                                      -6-
<PAGE>
termination date. All vested options which remain unexercised after the one year
anniversary of such termination date shall expire and terminate.

                  (vii) Continuation of Coverage.

                        (A)    If Executive's employment with the Company is
terminated under circumstances to which the provisions of Section 7(a)(iv),
Section 7(a)(v), Section 7(b)(iii) or Section 7(b)(vi) apply, the Company shall,
for the period during which the Company continues to pay Executive an amount
equal to his Base Salary and at its sole cost and expense, provide Executive and
his eligible dependents (if any) with healthcare, disability, and life insurance
benefits substantially similar to those benefits the Executive and his eligible
dependents (if any) were receiving immediately prior to the Executive's
termination of employment; provided, however,

                              (1)   the Company shall not be required to provide
medical coverage to the extent another employer provides comparable coverage,

                              (2)   with respect to death and disability
coverage, the Company shall not be required to provide coverage to the extent
another employer provides comparable coverage; and shall pay the cost of
supplemental coverage if a new employer provides less than comparable coverage,
to allow the Executive to purchase coverage to make total coverage comparable,
and

                              (3)   that the coverage provided by the Company
pursuant to this subsection 7(a)(vii)(A) shall be in lieu of any other continued
coverage for which the Executive or his dependents, if any, would otherwise be
eligible pursuant to COBRA.

                        (B)   If the Executive's employment with the Company is
terminated under circumstances to which the provisions of Section 7(a)(iv),
Section 7(a)(v), Section 7(b)(ii), Section 7(b)(iii) and Section 7(b)(vi) do not
apply, Executive (and his dependents, if any) shall be permitted to continue to
participate in the Company's benefit plans, programs, or arrangements to the
extent the Company is required by law, including Part 6 of Title I of the
Employee Retirement Income Security Act of 1974, as amended ("COBRA"), to offer
such coverage.

                  (viii)      No Offset.  Any compensation derived by the
Executive from any subsequent employment or self-employment shall not be offset
against or reduce any amounts to which the Executive is entitled under this
Agreement.

                                      -7-
<PAGE>
            (b) Termination After a Change of Control. If Executive's employment
with the Company is terminated after the effective date of a Change of Control,
Executive shall be entitled to receive severance benefits as follows:

                  (i) Parachute Payments. If all or any portion of the amounts
payable to the Executive under this Agreement or otherwise are subject to the
excise tax imposed by Section 4999 of the Internal Revenue Code of 1986, as
amended ("Code") or a similar state tax or assessment, the Company shall pay to
the Executive an amount necessary to place the Executive in the same after-tax
position as Executive would have been had no such excise tax or assessment been
imposed. The amount payable pursuant to the preceding sentence shall be
increased to the extent necessary to pay income and excise taxes on such amount.
The determination of any amounts payable under this Section 7(b)(i) shall be
made by an independent accounting firm employed by the Company and such
determination shall be final, binding and conclusion on the parties hereto.

                  (ii) Voluntary Resignation. If Executive's employment with the
Company is terminated by the Executive by reason of his voluntary resignation
within thirty (30) days after the anniversary date of the effective date of a
Change in Control, the Company shall pay or otherwise provide to the Executive
the following severance benefits:

                        (A)   a lump sum cash payment in an amount equal to the
lesser of two (2) times the Executive's current Base Salary at the time of
termination, or the Executive's current Base Salary at the time of termination
multiplied by the aggregate number of years (or any portion thereof, calculated
on a daily basis) remaining in the Employment Period had the Executive's
employment not been terminated, but in no event less than one full year,
provided that such amount shall be paid to the Executive within ten (10) days
after the date of termination;

                        (B)   until the earlier of the date the Employment
Period would otherwise have terminated had Executive's employment not been
terminated, or the expiration of the twenty-four (24) month period measured from
the date of the Executive's termination of employment, but in no event for less
than 12 months, the Company shall, at its sole cost and expense provide
Executive and his eligible dependents (if any) with healthcare, disability, and
life insurance benefits substantially similar to those benefits the Executive
and his eligible dependents (if any) were receiving immediately prior to the
Executive's termination of employment; provided, however,

                                      -8-
<PAGE>
                              (1)   the Company shall not be required to provide
medical coverage to the extent another employer provides comparable coverage,

                              (2)   with respect to death and disability
coverage, the Company shall not be required to provide coverage to the extent
another employer provides comparable coverage; and shall pay the cost of
supplemental coverage if a new employer provides less than comparable coverage,
to allow the Executive to purchase coverage to make total coverage comparable,
and

                              (3)   that the coverage provided by the Company
pursuant to this subsection 7(b)(ii)(B) shall be in lieu of any other continued
coverage for which the Executive or his dependents, if any, would otherwise be
eligible pursuant to COBRA; and

                        (C)   notwithstanding any provisions to the contrary
contained in the stock option agreements, Executive shall be permitted to
exercise all vested stock options until the one year anniversary of the date of
the Executive's termination of employment.

                  (iii) Termination by the Executive for Good Reason. If, after
the effective date of a Change of Control, Executive terminates his employment
with the Company for Good Reason, the Company shall pay or otherwise provide to
the Executive the severance benefits described in Section 7(a)(v) hereof.

                  (iv) Termination by Reason of Death. If, after the effective
date of a Change of Control, Executive's employment with the Company is
terminated by reason of Executive's death, the Company shall pay or otherwise
provide to Executive's designated beneficiary or beneficiaries the severance
benefits described in Section 7(a)(i) hereof.

                  (v) Termination by Reason of Disability. If, after the
effective date of a Change of Control, Executive's employment with the Company
is terminated by the Company by reason of Disability as described in Section
7(a)(ii) hereof, the Company shall pay or otherwise provide to Executive the
severance benefits described in that section.

                  (vi) Termination by the Company Other Than for Death,
Disability or Cause. If, after the effective date of a Change of Control,
Executive's employment with the Company is terminated by the Company other than
for Death, Disability, Voluntary Resignation or Cause, the Company shall pay or
otherwise provide to the Executive the severance benefits described in Section
7(a)(iv) hereof.

                                      -9-
<PAGE>
                  (vii) Termination by the Company for Cause. If, after the
effective date of a Change of Control, Executive's employment with the Company
is terminated by the Company for Cause, the Company shall pay Executive the
amounts described in Section 7(a)(iii) hereof.

                  (viii) Voluntary Termination by the Executive. If after the
effective date of a Change of Control, Executive voluntarily terminates his
employment with the Company under circumstances to which Section 7(b)(ii) does
not apply, the Company shall pay Executive the amounts described in Section
7(a)(vi).

                  Acceleration of Vesting. Any provisions of this Agreement
regarding vesting of stock options notwithstanding, the vesting of all
Previously Granted Stock Options shall be accelerated as described below upon
the occurrence of the following events:

                         Creeping Tender.  In the event of a Creeping Tender,
the unvested portion of the Previously Granted Stock Options shall become fully
vested and nonforfeitable as of the date that is ten business days before the
effective date of the Creeping Tender.

                        (A)    Acquisition Event.  Upon the execution by the
Company of an agreement to effect an Acquisition Event that is not a Creeping
Tender, the unvested portion of the Previously Granted Stock Options shall
become fully vested and nonforfeitable upon the occurrence of the Acquisition
Event or as of such earlier date as may be specified by the Board by written
notice to the Executive and the Board may take one or both of the following
actions with respect to the Previously Granted Stock Options: (I) provide that
the Previously Granted Stock Options shall be assumed, or equivalent stock
options be substituted by the acquiring or succeeding corporation (or an
affiliate thereof), or (II) upon written notice to the Executive, provide that
all then unexercised Previously Granted Stock Options will terminate to the
extent not exercised by the Executive prior to the consummation of such
Acquisition Event or such earlier date as may be specified by the Board by
written notice to the Executive.

                  (ix) Amendments to Stock Option Agreements. The Company and
the Executive agree promptly to take such steps to amend the Executive's
previously granted options to the extent necessary to reflect the provisions of
this Section 7.

      8. Proprietary Information; Company Documents and Materials.

            (a) Proprietary Information. Executive acknowledges that during the
Employment Period, Executive will occupy a position of trust and confidence with
respect to Proprietary Information of the Company.

                                      -10-
<PAGE>
Executive understands that he possesses or will possess Proprietary Information
that is important to the Company's business and operation. Executive
acknowledges that such Proprietary Information is specialized, unique in nature
and of great value to the Company and its Affiliates, and that such information
gives the Company and its Affiliates a competitive advantage. Executive
acknowledges that all Proprietary Information is and shall remain the sole
property of the Company or any of its Affiliates. Executive shall not disclose
to others or use, whether directly or indirectly, any Proprietary Information,
or anything relating to such information, regarding the Company or any of its
Affiliates; provided, however that Executive's obligations under this Section 8
shall not apply to any information that (i) is or becomes known to the general
public under circumstances involving no breach by Executive of the terms of this
Section 8, (ii) is generally disclosed to third parties by the Company without
restriction on such third parties, (iii) is approved for release by written
authorization of the Board of Directors or an authorized employee of the
Company, (iv) is communicated to Executive by a third party under no duty of
confidentiality with respect to such information to the Company or another
party, or (v) is required to be disclosed by Executive to comply with applicable
laws, governmental regulations, or court order, provided that Executive provides
prior written notice of such disclosure to the Company and an opportunity for
the Company to object to such disclosure and further provided that Executive
cooperates with the Company and takes reasonable and lawful actions requested by
the Company (the out-of-pocket costs of which shall be paid by the Company) to
avoid and/or minimize the extent of such disclosure.

            (b) Company Documents and Materials. Executive agrees that during
Executive's employment by the Company, Executive will not remove any Company
documents or materials, including Proprietary Information, from the business
premises of the Company or deliver any such Company documents or materials to
any person or entity outside the Company, except as Executive is required to do
in connection with performing the duties of Executive's employment. Executive
agrees that, immediately upon the termination of Executive's employment by
Executive or by the Company for any reason, or during Executive's employment if
so requested by the Company, Executive will return all Company documents and
materials, computer tapes and disks, records, lists, data, drawings, prints,
notes and written information, apparatus, equipment and other physical property,
or any reproduction of such property, excepting only (i) Executive's personal
copies of records relating to Executive's compensation; (ii) Executive's
personal copies of any materials previously distributed generally to
stockholders of the Company; and (iii) Executive's copy of this Agreement.

                                      -11-
<PAGE>
      9. Non-solicitation and Non-competition.

            (a) Non-solicitation. Executive agrees that during his employment
with the Company and for a period of one (1) year following the termination of
his employment with the Company, the Executive shall not hire, attempt to hire,
or assist in or facilitate in any way the hiring of any person who, at the time
of any such action by the Executive, is an employee of the Company (or any of
its Affiliates).

            (b) Non-competition. Executive agrees that if his employment with
the Company is terminated for any reason, including upon the expiration of the
Employment Period, for a period of one (1) year from the date of such
termination of employment, the Executive shall not, directly or indirectly, own,
manage, operate, control, be employed by, participate in, or be connected in any
manner with the ownership, management, operation or control of any company, or
any subsidiary or division of a company, more than 50% of whose annual revenues,
annual research and development expense (including the cost of research and
laboratory personnel) or income is attributable to the business of developing,
marketing or selling antisense therapeutics or oligonucleotide-based
immunostimulatory/immunoregulatory therapeutics or oligonucleotide-based
diagnostics.

      10. Assignment of Rights. All Executive Developments shall be made for
hire by Executive for the Company and Executive waives all moral rights. All
Executive Developments shall remain the sole property of the Company. Executive
shall acquire no proprietary interest in any Executive Developments developed or
acquired during the Employment Period. To the extent Executive may, by operation
of law or otherwise, acquire any right, title, or interest in or to any
Executive Development, Executive hereby assigns to the Company all such
proprietary rights. Executive shall, upon the Company's request, whether during
or after the Employment Period, promptly execute and deliver to the Company all
such assignments, certificates and instruments, and shall promptly perform such
other acts, as the Company may from time to time in its discretion deem
necessary or desirable to evidence, establish, maintain, perfect, enforce or
defend the Company's rights in Executive Developments.

      11. Successors. Any successor to the Company (whether direct or indirect
and whether by purchase, lease, merger, consolidation, liquidation or otherwise)
or to all or substantially all of the Company's business and/or assets shall
assume the obligations under this Agreement and shall perform the obligations
under this Agreement in the same manner and to the same extent as the Company
would be required to perform such obligations in the absence of a succession.
The Company may assign this Agreement without the Executive's consent to

                                      -12-
<PAGE>
any company that acquires all or substantially all of the Company's stock or
assets. Executive may not assign this Agreement and no person other than the
Executive (or his estate) may assert the Executive's rights under this
Agreement.

      12. Notice. All notices, requests, consents and other communications
hereunder ("Notices") to any party shall be contained in a written instrument
addressed to such party at the address set forth below or such other address as
may hereafter be designated in writing by the addressee to the addressor listing
all parties and shall be deemed given (a) when delivered in person or duly sent
by fax showing confirmation of receipt, (b) three days after being duly sent by
first class mail postage prepaid, or (c) two days after being duly sent by DHL,
Federal Express or other recognized express courier service:

            (a)   if to the Company, to:

                        Hybridon, Inc.
                        345 Vassar Street
                        Cambridge, MA 02139
                        fax: (617) 679-5582

            (b)   if to the Executive, to:

                        Robert G. Andersen
                        _____________________

                        _____________________

                        fax: ________________

      13. Company Plans. Except to the extent otherwise explicitly provided by
this Agreement, any awards made to the Executive under any Company compensation
or benefit plan, program, or arrangement shall be governed by the terms of that
plan, program, or arrangement and any applicable award agreement thereunder, as
in effect from time to time. Notwithstanding the preceding sentence, Executive
shall not be entitled to participate in any Company compensation or benefit
plan, program or arrangement that is established after his employment with the
Company terminates, and except as specifically provided in this Agreement,
Executive shall not be entitled to any additional grants or awards under any
Company compensation or benefit plan, program, or arrangement after his
employment with the Company terminates.

      14.   Miscellaneous Provisions.

            (a) Entire Agreement. This Agreement constitutes the entire
agreement between the parties and terminates and supersedes any and

                                      -13-
<PAGE>
all prior agreements and understandings (whether written or oral) between the
parties with respect to the subject matter of this Agreement. Executive
acknowledges and agrees that neither the Company, nor anyone acting on its
behalf has made, and in executing this Agreement Executive has not relied upon,
any representations, promises, or inducements except to the extent the same is
expressly set forth herein.

            (b) Waiver. No provision of this Agreement shall be modified,
waived, or discharged unless the modification, waiver, or discharge is agreed to
in writing and signed by Executive and by an authorized officer or
representative of the Company (other than Executive). No waiver by either party
of any breach of, or of compliance with, any condition or provision of this
Agreement by the other party shall be considered a waiver of any other condition
or provision or of the same condition or provision at a preceding or subsequent
time.

            (c) Capacity. The Executive represents and warrants to the Company
that he is not now under any obligation, of a contractual nature or otherwise,
to any person, firm, corporation, association or other entity that is
inconsistent, or in conflict, with this Agreement or which would prevent, limit
or impair in any way the performance by Executive of his obligations hereunder.

            (d) Consulting. Executive and the Company may, but are not required
to, enter into an agreement pursuant to which Executive will provide consulting
services to the Company after the date of Executive's retirement or termination
of employment with the Company. Any consulting fees paid to the Executive will
be in addition to any retirement or severance payments the Executive is entitled
to receive from the Company or under any plans, programs, or arrangements
maintained by the Company.

            (e) Severability. In the event that a court of competent
jurisdiction determines that any portion of this Agreement is in violation of
any law or public policy, only the portion of this Agreement that violates such
law or public policy shall be stricken. All portions of this Agreement that do
not violate any statute or public policy shall continue in full force and
effect. Further, any court order striking any portion of this Agreement shall
modify the stricken terms as narrowly as possible to give effect to the
intentions of the parties to this Agreement, as expressed herein.

            (f) Survival of Provisions. The obligations contained in Sections 8,
9 and 10 above shall survive the termination or expiration of the Employment
Period or this Agreement, as applicable, and shall be fully enforceable
thereafter in accordance with the terms of this Agreement.

                                      -14-
<PAGE>
            (g) Withholding. The Executive acknowledges that salary and all
other compensation payable under this Agreement shall be subject to withholding
for income and other applicable taxes to the extent required by law, as
determined by the Company in its sole discretion.

            (h) Headings. The headings or other captions contained in this
Agreement are for convenience of reference only and shall not be used in
interpreting, construing or enforcing any of the provisions of this Agreement.

            (i) Governing Law. This Agreement shall be governed by the laws of
the State of Massachusetts without giving effect to any conflict of law rules
that would require the application of the laws of any jurisdiction other than
the internal laws of the State of Massachusetts to the rights and duties of the
parties, except to the extent the laws of the State of Massachusetts are
preempted by federal law.

            (j) Terms. Where appropriate in this Agreement, words used in the
singular shall include the plural, and words used in the masculine shall include
the feminine or neuter.

            (k) Legal Fees. The Company shall pay or reimburse to the Executive
an amount equal to reasonable fees for legal representation incurred by the
Executive in connection with the preparation of this Agreement and the amendment
of existing options agreements in an amount not to exceed $6,000.

            (l) Counterparts. This Agreement may be executed in multiple
counterparts, each of which shall be deemed to be an original, and all of which
together shall constitute one agreement binding on the parties hereto.

      IN WITNESS WHEREOF, the parties hereto have executed this Agreement
effective as of the date first mentioned above.

HYBRIDON, INC.                             EXECUTIVE

BY:     /s/ James B. Wygaarden             BY: /s/ Robert G. Andersen
       --------------------------              --------------------------------
                                               Robert G. Andersen

TITLE:  Chairman                           DATE: April 1, 2002
       --------------------------              --------------------------------

DATE:   April 1, 2002
       --------------------------

                                      -15-
<PAGE>
                                   APPENDIX A

                                   DEFINITIONS

      ACCRUED OBLIGATIONS. "Accrued Obligations" shall mean the sum of (i) any
portion of Executive's Bonus accrued as of the date of termination of the
Executive's employment for any reason, including by reason of his death, which
has not yet been paid, and (ii) reimbursement of any reimbursable expense
incurred by the Executive through the date of termination of employment.

      ACQUISITION EVENT means

                  (i) any merger or consolidation which results in the voting
securities of the Company outstanding immediately prior thereto representing
(either by remaining outstanding or by being converted into voting securities of
the surviving or acquiring entity) less than 60% of the combined voting power of
the voting securities of the Company or such surviving or acquiring entity
outstanding immediately after such merger or consolidation;

                  (ii)  any sale of all or substantially all of the assets of
the Company;

                  (iii) the complete liquidation of the Company; or

                  (iv) the acquisition of "beneficial ownership" (as defined in
Rule 13d-3 under the Exchange Act) of securities of the Company representing 50%
or more of the combined voting power of the Company's then outstanding
securities (other than through a merger or consolidation or an acquisition of
securities directly from the Company) by any "person," as such term is used in
Sections 13(d) and 14(d) of the Exchange Act, other than the Company, any
trustee or other fiduciary holding securities under an employee benefit plan of
the Company or any corporation owned directly or indirectly by the stockholders
of the Company in substantially the same proportion as their ownership of stock
of the Company (an event specified in this clause (iv) being referred to as a
"Creeping Tender").

      AFFILIATE. "Affiliate" shall mean any person or entity which directly or
indirectly controls, is controlled by or is under common control with the
Company, including any entity directly or indirectly controlled by the Company
through the Company's ownership of fifty percent (50%) or more of the voting
interests of such entity.

      CAUSE. "Cause" shall mean Executive's (i) material breach of any material
terms of the Agreement, (ii) plea of guilty or nolo contendre to, or
<PAGE>
conviction of, the commission of a felony offense, (iii) repeated unexplained or
unjustified absence, or refusals to carry out the lawful directions of the Board
or (iv) material breach of a fiduciary duty owed to the Company under this
Agreement, provided that any action or inaction described by (i), (iii) or (iv),
above, shall not be the basis of a termination of the Executive's employment
with the Company for "Cause" unless the Company provided the Executive with at
least twenty (20) days advance written notice specifying in reasonable detail
the conduct in need of being cured and such conduct was not cured within the
notice period.

      CHANGE OF CONTROL.  "Change of Control" shall mean the occurrence of any
of the following events:

      (i) a change in the composition of the Board over a period of thirty-six
(36) consecutive months or less such that a majority of the members of the Board
ceases to be comprised of individuals who are Continuing Members; for such
purpose, a "Continuing Member" shall mean an individual who is a member of the
Board on the date of this Agreement and any successor of a Continuing Member who
is elected to the Board or nominated for election by action of a majority of
Continuing Members then serving on the Board; or

      (ii)  the consummation of an Acquisition Event.

      DISABILITY. "Disability" shall mean the inability of the Executive to
perform all the material duties of Executive's position for a continuous period
of at least ninety (90) days due to a permanent physical or mental impairment,
as determined and certified by a physician selected by the Executive and with
the concurrence of a physician selected by the Company, provided that if the
physician selected by the Executive and the physician selected by the Company do
not agree regarding the determination and certification, a determination and
certification rendered by an independent physician mutually agreed upon by the
Executive and the Company shall be final and binding on the parties with respect
to this Agreement.

      EXECUTIVE DEVELOPMENTS. "Executive Developments" shall mean any discovery,
invention, design, method, technique, improvement, enhancement, development, or
other work of authorship that (i) relates to the business or operation of the
Company then conducted or part of the Company's business plan, or (ii) results
from or is suggested by any undertaking assigned to the Executive or work
performed by Executive for or on behalf of the Company, whether or not during
working hours.

      GOOD REASON. "Good Reason" shall mean the occurrence of one or more of the
following: (i) any action by the Company which results in a material diminution
of Executive's position, title, annual base salary,

                                      -2-
<PAGE>
authority, duties or responsibilities or reporting structure; (ii) any material
breach of this Agreement by the Company which is not remedied by the Company
within thirty (30) days after receipt by the Company of notice thereof given by
Executive specifying in reasonable detail the alleged breach; or (iii)
relocation of the Company's headquarters outside the Cambridge Area or 10 miles
east of the Worcester area, except in the event of a change in the location of
the headquarters of the Company to a site within the continental United States
following a Change of Control.

      PROPRIETARY INFORMATION. "Proprietary Information" shall mean information
that was developed, created, or discovered by or on behalf of the Company, or
which became or will become known by, or was or is conveyed to the Company;
including, but not limited to, trade secrets, designs, technology, know-how,
processes, data, ideas, techniques, inventions (whether patentable or not),
works of authorship, formulae, business and development plans, client or
customer lists, software programs and subroutines, source and object code,
algorithms, terms of compensation and performance levels of Company employees,
information about the Company or any of its Affiliates, and their clients and
customers that is not disclosed by the Company or any of its Affiliates for
financial reporting purposes and that was learned by the Executive in the course
of employment by the Company or any of its Affiliates, other information
concerning the Company's actual or anticipated business, research or
development, or which is received in confidence by or for the Company from any
other person, and all papers, resumes, and records (including electronic or
computer-generated records) of the documents containing such Proprietary
Information. Proprietary Information shall not include information that is
publicly available or available through third party sources so long as it has
not become available through a breach of this Agreement by Executive.

                                      -3-

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