Exhibit 10.16


                                   ENZON, INC.
                               20 Kingsbridge Road
                          Piscataway, New Jersey 08854
                                 (732) 980-4500

                                  CONFIDENTIAL

                                                                    July 2, 2002

Via Hand Delivery
Jeffrey McGuire, Ph.D.
50 Durham Road
Easton, PA 18042

Re: Transition Agreement

Dear Jeff:

      This letter (the "Agreement") sets forth the agreement relating to your
resignation effective as of the close of business on July 2, 2002 (the
"Transition Date) from your current position as an officer of Enzon, Inc. (the
"Company") and our desire to employ you on a full-time basis, and your desire to
accept such full-time employment, during a transition period from the Transition
Date through July 31, 2002 (such date, or such earlier date on which your
employment with the Company terminates as provided in this Agreement, the
"Full-Time Termination Date").

      1. Your resignation as Senior Vice President, Scientific Affairs of the
Company is hereby accepted effective as of the Transition Date.

      2. Commencing on the Transition Date and ending on the Full-Time
Termination Date (the "Transition Period"), the Company will employ you on a
full-time basis and you will perform such duties and responsibilities as may be
assigned to you from time to time by the Chief Scientific Officer of the Company
(the "CSO"). You will report directly to the CSO. Your compensation for the
Transition Period will be Twenty Thousand Eight Hundred Thirty-Three Dollars and
Thirty-Three Cents ($20,833.33) per month payable in accordance with the
Company's customary payroll practices. During the Transition Period, you will be
entitled to participate on the same basis and at the same level as other
employees, in any group insurance, hospitalization, medical health and accident,
disability, similar plans or programs of the Company now existing or hereinafter
established to the extent that you are eligible under the general provisions
thereof. Without limiting the foregoing, during the Transition Period, your
stock options will continue to vest in accordance with their respective terms
and you will maintain the right to exercise any and all vested options while you
remain employed. The Company may terminate your employment at any time prior to
the Full-Time Termination Date only for "Cause." "Cause" will be limited to: (i)
your material breach of your duties (other than as a result of incapacity due to
physical or mental illness) which is demonstrably willful and deliberate on your
part, which is committed in bad faith or without reasonable belief that such


<PAGE>


Jeffrey McGuire, Ph.D.
July 2, 2002
Page 2

breach is in the best interests of the Company; (ii) your conviction of any
crime involving moral turpitude or any felony; or (iii) your willful engagement
in conduct that is demonstrably and materially injurious to the Company. You may
terminate your employment voluntarily on 30 days' prior notice to the Company
and your employment would also terminate on your death. If your employment is
terminated for "Cause," you will be entitled to compensation only through the
effective date of termination.

      3. Commencing on the date immediately following the Full-Time Termination
Date, you will continue to work up to five (5) hours per month for the Company
as a part-time employee as requested by the Company through July 1, 2003. You
may perform the part-time employment required pursuant to this paragraph 3 by
phone, if acceptable to the Company, or at the Company's offices in Piscataway,
New Jersey. The Company will use its best efforts to aggregate services
requested in a month. For purposes of the Company's Non-Qualified Stock Option
Plan and determining the vesting of options granted to you under such Plan, the
Compensation Committee has determined that you will continue to be deemed to be
an employee of the Company during the period in which you work for the Company
as a part-time employee or make yourself available to work for the Company as a
part-time employee pursuant to this paragraph 3, provided that if you refuse or
fail to provide such part-time services, or if you accept Full-Time Employment
with any other employer during such period, or you die during such period, you
will no longer be deemed to be an employee of the Company for such purposes as
of the date you refuse or fail to provide such part-time services, or the date
you commence such Full-Time Employment, or the date you die. For purposes of
this Agreement, Full-Time Employment will mean employment in which you work at
least 37.5 hours per week. In accordance with the terms of the Company's
Non-Qualified Stock Option Plan and the options granted to you under such Plan,
as of the date you are no longer deemed an employee under this paragraph or
otherwise, all vesting of stock options will cease but you will have 190 days
thereafter in which to exercise any or all stock options vested as of the date
you are no longer deemed an employee of the Company (or until such earlier
date(s) as the options will expire by their respective terms); provided,
however, if you are no longer deemed an employee by reason of your death, the
executors or administrators, or legatees or heirs, of your estate will have the
right to exercise the options to the extent that you were entitled to exercise
the options on the date of your death from time to time thereafter, but in no
event following the date which is ten years from the date the options were
granted.

      4. On or before the Full-Time Termination Date, you will execute a release
in the form attached hereto as Exhibit A (the "Bring-Down Release"), releasing
the Company from any claims you may have against it relating to your employment
as provided in paragraph 2.

      5. In consideration for signing this Agreement and in exchange for the
promises, covenants and waivers set forth herein, provided you have not revoked
this Agreement as set forth below and subject to your compliance with its terms,
including but not limited to execution and delivery of the Bring-Down Release by
the Full-Time Termination Date, and your not revoking the Bring-Down Release as
provided therein, and provided that your employment has not been terminated for
Cause as set forth in Paragraph 2 above:


<PAGE>

Jeffrey McGuire, Ph.D.
July 2, 2002
Page 3

      a.    For eleven (11) months commencing on August 1, 2002 the Company will
            pay you Twenty Thousand Eight Hundred Thirty-Three Dollars and
            Thirty-Three Cents ($20,833.33) per month payable in accordance with
            the Company's customary payroll practices. If you wish to receive a
            lump sum payment for the balance of the remainder of the above
            stated severance pay, you must notify the company of your intention
            in writing 30 days prior to receiving such payment. On the date you
            receive your lump sum payment your Part-Time employment with the
            Company will cease along with all benefits provided to part-time
            employees,and your stock options will no longer continue to vest
            except as specifically provided by the applicable plan document.

      b.    You will be entitled to participate in the bonus pool which may be
            awarded to officers of the Company for the fiscal year ending June
            30, 2002. The amount of the award will be based both on your
            performance and that of the Company during the fiscal year 2002. The
            bonus amount will be made available in August, when such bonus
            payments are normally paid to officers of the Company, and will be
            subject to all applicable taxes, including but not limited to state
            and federal income and employment taxes. Nothing contained herein
            will guarantee that any bonus will be paid to you and you will only
            receive a bonus as determined hereunder if the other officers of the
            Company are awarded a bonus.

      c.    The Company agrees to provide you, and any spouse and/or dependents
            receiving medical and dental coverage as of your severance date
            under a group health plan sponsored by the Company ("Family
            Members"), with continued group health coverage, including medical
            and dental coverage, as otherwise required under applicable state
            continuation law and the Consolidated Omnibus Budget Reconciliation
            Act of 1986 ("COBRA"). The Company will reimburse you for the total
            applicable premium cost for medical and dental COBRA continuation
            coverage elected for you and your Family Members for a period of up
            to eleven (11) months commencing on the Full-Time Termination Date.
            In the event you obtain Full-Time Employment within eleven (11)
            months of the Full-Time Termination Date with an entity other than
            the Company, and you and your Family Members become eligible for a
            group health plan of such entity providing medical and/or dental
            coverage, the Company's obligation to reimburse you for the total
            applicable premium cost of medical and dental continuation coverage
            elected will cease as of the date such coverage for you and your
            Family Members under such group health plan becomes effective. As a
            condition of receiving the continuing medical and dental coverage,
            you will be required to notify Human Resources promptly following
            the date on which you obtain Full-Time Employment with another
            company.


<PAGE>

Jeffrey McGuire, Ph.D.
July 2, 2002
Page 4

      d.    You will also receive a lump sum payment for any accrued and unused
            2002 Compensated Time Off as of the Full-Time Termination Date.

      6. In the event you die during the period in which you are entitled to the
benefits provided in paragraph 5(c) hereof, the Company will continue to
reimburse your Family Members for the premium cost for COBRA continuation
coverage through the date which is eleven (11) months from the Full-Time
Termination Date.

      7. This Agreement is unfunded. No fund is being set aside or allocated
specifically for the purpose of this Agreement. All payments hereunder will be
paid out of the general assets of the Company. You will not have any secured or
preferred interest by way of a trust, escrow, lien or otherwise in any specific
asset of the Company for unpaid payments under this Agreement.

      8. The Company may withhold from any amounts payable under this Agreement
such Federal, state or local taxes as will be required to be withheld pursuant
to any applicable law or regulation.

      9. We hereby agree that the Employee Retention Agreement dated August 3,
2001 (the "Employee Retention Agreement") between you and the Company, is hereby
terminated and of no further force and effect.

      10. In consideration of the payments and benefits described in paragraph 5
of this Agreement, and for other good and valuable consideration, you hereby
release and forever discharge, and by this instrument release and forever
discharge, the Company and its subsidiaries and their respective successors,
assigns, representatives, agents, attorneys, shareholders, officers, directors
and employees (the "Company Released Parties"), from all debts, obligations,
promises, covenants, agreements, contracts, endorsements, bonds, controversies,
suits, actions, causes of action, judgments, damages, expenses, claims or
demands, in law or in equity, which you ever had, now have, or which may arise
in the future, regarding any matter arising on or before the date of execution
of this Agreement, including but not limited to all claims (whether known or
unknown) regarding your employment at or termination of employment from the
Company, any contract (express or implied), any claim for equitable relief or
recovery of punitive, compensatory, or other damages or monies, attorneys' fees,
any tort, and all claims for alleged discrimination based upon age, race, color,
sex, sexual orientation, marital status, religion, national origin, handicap,
disability, or retaliation, including any claim, asserted or unasserted, which
could arise under Title VII of the Civil Rights Act of 1964; the Equal Pay Act
of 1963; the Age Discrimination in Employment Act of 1967; the Older Workers
Benefit Protection Act of 1990; the Americans With Disabilities Act of 1990; the
Civil Rights Act of 1866, 42 U.S.C., 1981; the Employee Retirement Income
Security Act of 1974; the Family and Medical Leave Act of 1993; the Civil Rights
Act of 1991; the Worker Adjustment and Retraining Notification Act of 1988; the
New Jersey Conscientious Employee Protection Act; the New Jersey Law Against
Discrimination; and any other federal, state or local laws, rules or
regulations, whether equal employment opportunity laws, rules or regulations or
otherwise, or any right under any of the Company's pension, welfare, or stock
plans. The foregoing release by you does not apply to any of your rights under
this Agreement.

<PAGE>

Jeffrey McGuire, Ph.D.
July 2, 2002
Page 5

      11. You represent and agree that you have not filed any lawsuits against
any of the Company Released Parties, or filed or caused to be filed any charges
or complaints against any of the Company Released Parties with any municipal,
state or federal agency charged with the enforcement of any law. You also agree,
to the extent consistent with applicable law, not to initiate any legal action,
complaint, statement of claim or demand for arbitration against any Company
Released Parties in any forum whatsoever, in connection with the claims released
hereby. In addition, to the extent any such action may be brought, you expressly
waive any claim to any form of monetary or other damages, or any other form of
recovery or relief in connection with any such action, or in connection with any
action brought by a third party. If you violate this Agreement by filing or
bringing any claims or actions contrary to this paragraph, you will immediately
forfeit all right to any and all future payments or services, as the case may
be, if any, under paragraph 5 of this Agreement. You also agree to pay all costs
and expenses of any Company Released Party in defending against such claims or
actions brought by you, including reasonable attorneys' fees.

      12. You represent, warrant and acknowledge that the Company owes you no
wages, commissions, bonuses, sick pay, personal leave pay, severance pay,
vacation pay or other compensation or payments or form of remuneration of any
kind or nature, other than that specifically provided for in this Agreement and
under the stock option certificates dated July 21, 1998, July 20, 1999 and July
31, 2000 (collectively, the "Stock Option Certificates").

      13. You will not disparage or criticize any of the Company Released
Parties, or issue any communication, written or otherwise, that reflects
adversely on or encourages any adverse action against any Company Released
Parties, except if testifying truthfully under oath pursuant to any lawful court
order or subpoena or otherwise responding to or providing disclosures required
by law.

      14. Upon service on you of any subpoena, order, directive or other legal
process requiring you or the Company to engage in conduct encompassed within
paragraphs 11 and 13 of this Agreement, you will immediately notify the Company
of such service and of the content of any testimony or information to be
provided pursuant to such subpoena, order directive or other legal process and
within two (2) business days send to the Company, via overnight delivery, a copy
of said document served upon you.

      15. You will assist and cooperate with the Company in connection with the
defense or prosecution of any claim that may be made against or by the Company,
or in connection with any ongoing or future investigation or dispute or claim of
any kind involving the Company, including any proceeding before any arbitral,
administrative, judicial, legislative, or other body or agency, including
testifying in any proceeding to the extent such claims, investigations or
proceedings relate to services performed or required to be performed by you,
pertinent knowledge possessed by you, or any act or omission by you. You will
perform all acts and execute and deliver any documents that may be reasonably
necessary to carry out the provisions of this paragraph. The Company will pay
you a per diem, as reasonably requested by you, and reimburse you for all
expenses incurred pursuant to this paragraph.


<PAGE>

Jeffrey McGuire, Ph.D.
July 2, 2002
Page 6

      16. The "Noncompete Period" will commence upon execution of this Agreement
and continue through the date which is eleven (11) months following the
Full-Time Termination Date. In consideration for the benefits provided to you
under this Agreement, during the Noncompete Period, you will not directly or
indirectly, whether as an officer, director, stockholder, partner, proprietor,
associate, employee, consultant, representative or otherwise, become, or be
interested in or associated with any other person, corporation, firm,
partnership or entity, engaged to a significant degree in (x) developing,
marketing or selling enzymes, protein-based biopharmaceuticals or other
pharmaceuticals that are modified using polyethylene glycol ("PEG") or PEG
containing polymers, (y) developing, marketing or selling single-chain
antigen-binding proteins or polypeptides or (z) any technology or area of
business in which the Company becomes involved to a significant degree during
the term of your Full-Time Employment with the Company. For purposes of the
preceding sentence, to determine whether any entity is engaged in such
activities to a "significant degree" comparison will be made to the Company's
operations at that time. In other words, an entity will be deemed to be engaged
in an activity to a significant degree if the number of employees and/or amount
of funds devoted by such entity to such activity would be material to the
Company's operations at that time. Notwithstanding anything to the contrary
contained herein, you will be entitled to work with or for (i) an entity that is
developing, marketing or manufacturing monoclonal antibodies, (ii) a licensee of
the Company if the only activities conducted by such licensee that would be
covered by the restrictions in this paragraph 16 are conducted pursuant to, and
covered by, the license granted by the Company and (iii) an entity that is
engaged in a research project that would be covered by the restrictions in this
paragraph 16 if such research project is not material to such entity and you
would have no direct involvement in such research project; provided in the case
of employment covered by clauses (ii) and (iii) you will have provided the Board
of Directors of the Company (the "Board") with a detailed description of the
proposed employment and obtained the written consent of the Board (which consent
will not be unreasonably withheld) prior to commencing any such employment. You
are hereby prohibited from ever using any of the Company's proprietary
information or trade secrets to conduct any business, except for the Company's
business, while you are employed by the Company. The provision contained in the
preceding sentence will survive the termination of your employment with the
Company. In the event you breach any of the covenants set forth in this
paragraph 16, the running of the period of restriction set forth herein will
cease and will recommence upon your compliance with the terms of this paragraph
16. Notwithstanding the above, ownership by you, as a passive investment, of
less than five percent of the outstanding shares of capital stock of any
corporation listed on a national securities exchange or publicly traded on
Nasdaq will not constitute a breach of this paragraph 16.

      17. You recognize and acknowledge that information relating to the
Company's business, including, but not limited to, information relating to
patent applications filed or to be filed by the Company, trade secrets relating
to the Company's products or services, and information relating to the Company's
research and development activities, will be and remain the sole and exclusive
property of the Company and are valuable, special and unique assets of the
Company's business. You will not, during or after the term of your employment by
the Company, disclose any such information to any person, corporation, firm,
partnership or other


<PAGE>

Jeffrey McGuire, Ph.D.
July 2, 2002
Page 7

entity. The provisions of this paragraph 17 will survive the termination of your
employment with the Company.

      18. You agree that the covenants and agreements contained in paragraphs 16
and 17 are material to this Agreement; that each of such covenants is reasonable
and necessary to protect and preserve the Company's interests, properties and
business; that irreparable loss and damage will be suffered by the Company
should you breach any of such covenants and agreements; that given the unique
nature of the Company's business such loss and damage would be suffered by the
Company regardless of where a breach of such covenants and agreements occur,
thus making the absence of a geographical limitation reasonable; that each of
such covenants and agreements is separate, distinct and severable not only from
the other of such covenants and agreements but also from the other and remaining
provisions of this Agreement; that the unenforceability or breach of any such
covenant or agreement will not affect the validity or enforceability of any
other such covenant or agreement or any other provision of this Agreement; and
that, in addition to other remedies available to it, the Company will be
entitled to both temporary and permanent injunctions and any other rights or
remedies it may have, at law or in equity, to prevent a breach or contemplated
breach by you of any such covenants or agreements. Notwithstanding anything
herein to the contrary, if a period of time or other restriction specified in
paragraphs 16 or 17 should be determined to be unreasonable in a judicial
proceeding, then the period of time or other restriction will be revised so that
the covenants contained in paragraph 16 or 17 may be enforced during such period
of time and in accordance with such other restrictions as may be determined to
be reasonable.

      19. You agree to assign and do hereby assign to the Company all tangible
and intangible property, including, but not limited to, inventions, developments
or discoveries conceived, reduced to practice, made or discovered by you solely
or in collaboration with others during the term of your employment with the
Company, which relate in any manner to the subject manner expressed in paragraph
16 (x), (y) and (z) of this Agreement.

      20. Prior to the Full-Time Termination Date, you will deliver to the
Company and retain no copies of any written materials, records and documents
made by you or coming into your possession during the course of your employment
with the Company which contain or refer to any proprietary or confidential
information of the Company. Prior to the Full-Time Termination Date, you will
deliver to the Company any and all property and equipment of the Company.

      21. In the event you materially breach this Agreement, in addition to the
remedies set forth in paragraph 18, the Company will be entitled to recover
and/or discontinue any payment and/or other benefits paid or payable under this
Agreement and to obtain all other relief provided by law or equity. The
prevailing party in any litigation resulting from any such claim will be
entitled to recover reasonable attorneys' fees and expenses of litigation from
the losing party.

      22. This Agreement together with the Bring-Down Release constitutes the
entire agreement between the Company and you, and supersedes and cancels all
prior written and oral agreements, if any, between the Company and you, except
that the Stock Option Certificates will continue in full force and effect in
accordance with their respective terms. You and the

<PAGE>

Jeffrey McGuire, Ph.D.
July 2, 2002
Page 8

Company acknowledge that, in entering into this Agreement, you are not relying
upon any oral or written promise or statement made by anyone at any time.

      23. This Agreement is binding upon you and the Company and your or its
successors, assigns, heirs, executors, administrators and legal representatives,
as the case may be.

      24. If any of the provisions, terms or clauses of this Agreement are
declared illegal, unenforceable or ineffective in a legal forum, those
provisions, terms and clauses will be deemed severable, such that all other
provisions, terms and clauses of this Agreement will remain valid and binding
upon both parties. However, the illegality or unenforceability of any such
provision will have no effect upon, and will not impair the enforceability of
the release language set forth in paragraph 10, provided that, upon a finding by
a court of competent jurisdiction that the release language found in paragraph
10 is unenforceable, the parties will rewrite paragraph 10 to cure the defect
and you and a representative of the Company will reexecute the release and
neither party will be entitled to any additional monies, benefits and/or
compensation therefor.

      25. Without detracting in any respect from any other provision of this
Agreement:

      a.    You, in consideration of the payments described in paragraph 5 of
            this Agreement, and for other good and valuable consideration, agree
            and acknowledge that this Agreement constitutes a knowing and
            voluntary waiver of all rights or claims you have or may have
            against the Company Released Parties as set forth herein, including,
            but not limited to, all rights or claims arising under the Age
            Discrimination in Employment Act of 1967, as amended ("ADEA"),
            including, but not limited to, all claims of age discrimination in
            employment and all claims of retaliation in violation of the ADEA;
            that you have no physical or mental impairment of any kind that has
            interfered with your ability to read and understand the meaning of
            this Agreement or its terms; and that you are not acting under the
            influence of any medication or mind-altering chemical of any type in
            entering into this Agreement.

      b.    You understand that, by entering into this Agreement, you do not
            waive rights or claims that may arise after the date of your
            execution of this Agreement, including without limitation any rights
            or claims that you may have to secure enforcement of the terms and
            conditions of this Agreement.

      c.    You agree and acknowledge that the consideration provided to you
            under this Agreement for the releases and waivers contained herein
            is in addition to anything of value to which you are already
            entitled.

      d.    The Company hereby advises you to consult with an attorney prior to
            executing this Agreement.


<PAGE>

Jeffrey McGuire, Ph.D.
July 2, 2002
Page 9

      e.    You acknowledge that you were informed that you had at least
            twenty-one (21) days in which to review and consider this Agreement,
            and to consult with an attorney regarding the terms and effect of
            this Agreement.

      26. The Company agrees that you may revoke this Agreement within seven (7)
days from the date you sign this Agreement, in which case this Agreement will be
null and void and of no force or effect on either the Company or you. Any
revocation must be in writing and received by the Company by 5:00 p.m. on or
before the seventh day after this Agreement is executed by you. Such revocation
must be sent to:

                                   ENZON, INC.
                               20 Kingsbridge Road
                          Piscataway, New Jersey 08854
                              Attention: Paul Davit

      27. This Agreement may not be changed or altered, except by a writing
signed by the Company and you. This Agreement is entered into in the State of
New Jersey, and the laws of the State of New Jersey will apply to any dispute
concerning it, excluding the conflict-of-law principles thereof.

      28. This Agreement may be executed in counterparts, each of which will be
deemed an original, but all of which, when taken together, will constitute one
and same instrument

      YOU EXPRESSLY ACKNOWLEDGE, REPRESENT, AND WARRANT THAT YOU HAVE READ THIS
AGREEMENT CAREFULLY; THAT YOU FULLY UNDERSTAND THE TERMS, CONDITIONS, AND
SIGNIFICANCE OF THIS AGREEMENT; THAT THE COMPANY HAS ADVISED YOU TO CONSULT WITH
AN ATTORNEY CONCERNING THIS AGREEMENT; THAT YOU HAVE HAD A FULL OPPORTUNITY TO
REVIEW THIS AGREEMENT WITH AN ATTORNEY; THAT YOU UNDERSTAND THAT THIS AGREEMENT
HAS BINDING LEGAL EFFECT; AND THAT YOU HAVE EXECUTED THIS AGREEMENT FREELY,
KNOWINGLY AND VOLUNTARILY.


<PAGE>

Jeffrey McGuire, Ph.D.
July 2, 2002
Page 10

      PLEASE READ CAREFULLY. THIS AGREEMENT HAS IMPORTANT LEGAL CONSEQUENCES.


Date: July 2, 2002

                                      ENZON, INC.


                                      By:
                                          --------------------------------------
                                          Name: Paul Davit
                                          Title: Vice President, Human Resources

AGREED AND ACCEPTED:


------------------------

JEFFREY MCGUIRE, PH.D.


On this ____ day of _____, 2002, before me personally came Jeff McGuire, Ph.D.,
to me known to be the individual described in the foregoing instrument, who
executed the foregoing instrument in my presence, and who duly acknowledged to
me that he executed the same.


                                      ------------------------------------------
                                      Notary Public

You must sign and return this Agreement to the Company no later than 5:00 p.m.
on the 21st day following receipt of this document or irrevocably lose the
opportunity to receive the consideration detailed herein. You received this
Agreement on July 2, 2002.


<PAGE>


                                    EXHIBIT A


                             Jeffrey McGuire, Ph.D.
                                 50 Durham Road
                                Easton, PA 18042


                                                     _________________, 2002

Enzon, Inc.
20 Kingsbridge Road
Piscataway, New Jersey 08854
Attention:  Paul Davit

Gentlemen:

      I am executing and delivering this release (the "Release") pursuant to
paragraph 4 of the Transition Agreement (the "Agreement") dated ___________,
2002, between Enzon, Inc. (the "Company") and me. Unless otherwise defined
herein, capitalized terms used in this Release shall have the meanings ascribed
to them in the Agreement.

      In consideration of the payments and benefits described in paragraph 5 of
the Agreement, and for other good and valuable consideration, I hereby release
and forever discharge, and by this instrument release and forever discharge, the
Company and its subsidiaries and their respective successors, assigns,
representatives, agents, attorneys, shareholders, officers, directors and
employees (the "Company Released Parties"), from all debts, obligations,
promises, covenants, agreements, contracts, endorsements, bonds, controversies,
suits, actions, causes of action, judgments, damages, expenses, claims or
demands, in law or in equity, which I ever had, now have, or which may arise in
the future, regarding any matter arising on or before the date of execution of
this Release, including but not limited to all claims (whether known or unknown)
regarding my employment at or termination of employment from the Company, any
contract (express or implied), any claim for equitable relief or recovery of
punitive, compensatory, or other damages or monies, attorneys' fees, any tort,
and all claims for alleged discrimination based upon age, race, color, sex,
sexual orientation, marital status, religion, national origin, handicap,
disability, or retaliation, including any claim, asserted or unasserted, which
could arise under Title VII of the Civil Rights Act of 1964; the Equal Pay Act
of 1963; the Age Discrimination in Employment Act of 1967; the Older Workers
Benefit Protection Act of 1990; the Americans With Disabilities Act of 1990; the
Civil Rights Act of 1866, 42 U.S.C., 1981; the Employee Retirement Income
Security Act of 1974; the Family and Medical Leave Act of 1993; the Civil Rights
Act of 1991; the Worker Adjustment and Retraining Notification Act of 1988; the
New Jersey Conscientious Employee Protection Act; the New Jersey Law Against
Discrimination; and any other federal, state or local laws, rules or
regulations, whether equal employment opportunity laws, rules or regulations or
otherwise, or any right under any of the Company's pension, welfare, or stock
plans. The foregoing release by me does not apply to any of my rights under the
Agreement.


<PAGE>


Enzon, Inc.
Page 2

      I represent and agree that I have not filed any lawsuits against any of
the Company Released Parties, or filed or caused to be filed any charges or
complaints against any of the Company Released Parties with any municipal, state
or federal agency charged with the enforcement of any law. I also agree, to the
extent consistent with applicable law, not to initiate any legal action,
complaint, statement of claim or demand for arbitration against any Company
Released Parties in any forum whatsoever, in connection with the claims released
hereby. In addition, to the extent any such action may be brought, I expressly
waive any claim to any form of monetary or other damages, or any other form of
recovery or relief in connection with any such action, or in connection with any
action brought by a third party. If I violate this covenant by filing or
bringing any claims or actions contrary to this paragraph, I will immediately
forfeit all right to any and all future payments or services, as the case may
be, if any, under paragraph 5 of the Agreement. I also agree to pay all costs
and expenses of any Company Released Party in defending against such claims or
actions brought by me, including reasonable attorneys' fees.

      Without detracting in any respect from any other provision of this
Release:

            a.    I, in consideration of the payments described in paragraph 5
                  of the Agreement, and for other good and valuable
                  consideration, agree and acknowledge that this Release
                  constitutes a knowing and voluntary waiver of all rights or
                  claims I have or may have against the Company Released Parties
                  as set forth herein, including, but not limited to, all rights
                  or claims arising under the Age Discrimination in Employment
                  Act of 1967, as amended ("ADEA"), including, but not limited
                  to, all claims of age discrimination in employment and all
                  claims of retaliation in violation of the ADEA; that I have no
                  physical or mental impairment of any kind that has interfered
                  with my ability to read and understand the meaning of this
                  Release or its terms; and that I am not acting under the
                  influence of any medication or mind-altering chemical of any
                  type in entering into this Release.

            b.    I understand that, by entering into this Release, I do not
                  waive rights or claims that may arise after the date of my
                  execution of this Release, including without limitation any
                  rights or claims that I may have to secure enforcement of the
                  terms and conditions of this Release.

            c.    I agree and acknowledge that the consideration provided to me
                  under the Release for the releases and waivers contained
                  herein is in addition to anything of value to which I am
                  already entitled.

            d.    The Company hereby advises me to consult with an attorney
                  prior to executing this Release.

            e.    I acknowledge that I was informed that I had at least
                  twenty-one (21) days in which to review and consider this
                  Release, and to consult with an attorney regarding the terms
                  and effect of this Release.

<PAGE>


Enzon, Inc.
Page 3

      The Company agrees that I may revoke this Release within seven (7) days
from the date I sign this Release, in which case this Release will be null and
void and of no force or effect on either the Company or me. Any revocation must
be in writing and received by the Company by 5:00 p.m. on or before the seventh
day after this Release is executed by me. Such revocation must be sent to:

                                   ENZON, INC.
                               20 Kingsbridge Road
                          Piscataway, New Jersey 08854
                              Attention: Paul Davit

      This Release may not be changed or altered, except by a writing signed by
the Company and me. This Release is entered into in the State of New Jersey, and
the laws of the State of New Jersey will apply to any dispute concerning it,
excluding the conflict-of-law principles thereof.


<PAGE>


Enzon, Inc.
Page 4

      This Release may be executed in counterparts, each of which will be deemed
an original, but all of which, when taken together, will constitute one and same
instrument

      I EXPRESSLY ACKNOWLEDGE, REPRESENT, AND WARRANT THAT I HAVE READ THIS
RELEASE CAREFULLY; THAT I FULLY UNDERSTAND THE TERMS, CONDITIONS, AND
SIGNIFICANCE OF THIS RELEASE; THAT THE COMPANY HAS ADVISED ME TO CONSULT WITH AN
ATTORNEY CONCERNING THIS RELEASE; THAT I HAVE HAD A FULL OPPORTUNITY TO REVIEW
THIS RELEASE WITH AN ATTORNEY; THAT I UNDERSTAND THAT THIS RELEASE HAS BINDING
LEGAL EFFECT; AND THAT I HAVE EXECUTED THIS RELEASE FREELY, KNOWINGLY AND
VOLUNTARILY.

      PLEASE READ CAREFULLY. THIS RELEASE HAS IMPORTANT LEGAL CONSEQUENCES.


Date: __________, 2002

                                             ---------------------
                                             JEFFREY MCGUIRE, PH.D.

On this ____ day of _____, 2002, before me personally came Jeffrey McGuire,
Ph.D., to me known to be the individual described in the foregoing instrument,
who executed the foregoing instrument in my presence, and who duly acknowledged
to me that he executed the same.


                                             -----------------------------------
                                             Notary Public

RECEIPT ACKNOWLEDGED:

ENZON, INC.

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