Exhibit 10.13

                          EMPLOYEE RETENTION AGREEMENT

     AGREEMENT  by  and  between  Enzon,  Inc.,  a  Delaware   corporation  (the
"Company"),  and [            ](the  "Employee"),  dated  as of the  3rd  day of
August, 2001 (the "Effective Date").

     WHEREAS, the Board of Directors of the Company (the "Board") has determined
that it is in the best interests of the Company and its  stockholders  to assure
that the  Company  will  have  the  continued  services  and  dedication  of the
Employee,  notwithstanding  the  change in the chief  executive  officer  of the
Company which occurred on May 31, 2001 ("Change in CEO").  The Board believes it
is imperative to diminish the  inevitable  distraction of the Employee by virtue
of the  personal  uncertainties  and risks  created  by the Change in CEO and to
encourage the  Employee's  full  attention and  dedication to the Company and to
provide the Employee with  compensation and benefits  arrangements  which ensure
that  the  compensation  and  benefits  expectations  of the  Employee  will  be
satisfied and are competitive with those of other  corporations.  Therefore,  in
order to accomplish these objectives,  the Board has caused the Company to enter
into this Agreement.

     NOW, THEREFORE, IT IS HEREBY AGREED AS FOLLOWS:

1. CERTAIN DEFINITIONS

     (a) Annual Base Salary. "Annual Base Salary" shall mean the salary which is
paid as  consideration  for the  Employee's  service  during the calendar  year,
excluding  any  special  form  of  compensation,  cash  or  otherwise,  such  as
incentives,  commissions,  bonuses,  stock options or other stock based forms of
compensation or any type of fringe benefit.

     (b) Cause. "Cause" shall mean:

          (i) a material breach by the Employee of the Employee's  duties (other
     than as a result of incapacity due to physical or mental  illness) which is
     demonstrably  willful  and  deliberate  on the  Employee's  part,  which is
     committed in bad faith or without  reasonable belief that such breach is in
     the best interests of the Company;

          (ii) the Employee's  conviction of any crime involving moral turpitude
     or any felony; or

          (iii)  the  willful  engaging  by the  Employee  in  conduct  that  is
     demonstrably and materially injurious to the Company.

     (c)  Compensation  Committee.   "Compensation  Committee"  shall  mean  the
Compensation  Committee  of the Board or such  other  Committee  of the Board as
shall administer the Company's option plans.

     (d) Date of Termination.  "Date of Termination" means (i) if the Employee's
Full-Time Employment with the Company is terminated by the Company for Cause, or
by the  Employee  for  Good  Reason,  the  date  of  receipt  of the  Notice  of
Termination or any later date


                                      E-2
<PAGE>

specified  therein,  as the case may be,  and (ii) if the  Employee's  Full-Time
Employment  with the Company is  terminated by the Company other than for Cause,
the Date of  Termination  shall be the date on which the  Company  notifies  the
Employee of such termination.

     (e)  Employment  Period.  "Employment  Period" began as of May 31, 2001 and
ends as of the close of business on May 30, 2002.

     (f) Full-Time Employment.  "Full-Time Employment" shall mean employment for
at least 37.5 hours per week.

     (g) Good Reason. "Good Reason" shall mean:

          (i)  a  diminution  in  the  Employee's  position  (including  status,
     offices,   title  and  reporting   requirements),   authority,   duties  or
     responsibilities  or any other  action by the  Company  which  results in a
     diminution  in  such  position,   authority,  duties  or  responsibilities,
     excluding  for this  purpose an  isolated,  insubstantial  and  inadvertent
     action not taken in bad faith and which is remedied by the Company promptly
     after receipt of notice thereof given by the Employee;

          (ii) the Company's requiring the Employee to be based at any office or
     location  other  than  (A)  the  office  located  at 20  Kingsbridge  Road,
     Piscataway,  New Jersey,  or (B) any office  which is less than twenty (20)
     miles from such location;

          (iii) a reduction by the Company in the Employee's  Annual Base Salary
     below the Annual  Base  Salary  payable to by  Employee  as of the date the
     Employment Period began; or

          (iv) the failure by the  Company to provide  employee  benefit  plans,
     programs, policies and practices (including, without limitation, retirement
     plans and medical,  dental, life and disability  insurance coverage) to the
     Employee and the  Employee's  family and dependents  (if  applicable)  that
     provide  substantially  similar  benefits,  in terms of aggregate  monetary
     value,  to the  Employee  and the  Employee's  family  and  dependents  (if
     applicable) at substantially  similar costs to the Employee as the benefits
     provided by those plans,  programs,  policies and practices in effect as of
     the date the Employment Period began.

For purposes of this Section 1(g), any good faith determination of "Good Reason"
made by the Employee shall be conclusive.

     (h) Notice of  Termination.  Any termination by the Company for Cause or by
the Employee for Good Reason during the Employment  Period shall be communicated
by Notice of  Termination  to the other party  hereby given in  accordance  with
Section 8(b). For purposes of this Agreement,  a "Notice of Termination" means a
written  notice which (i) indicates the specific  termination  provision in this
Agreement relied upon, (ii) to the extent  applicable,  sets forth in reasonable
detail the facts and circumstances claimed to provide a basis for termination of
the Employee's employment under the provision so indicated and (iii) if the Date
of Termination  is other than the date of receipt of such notice,  specifies the
termination  date (which date shall be not more than 15 days after the giving of
such  notice).  The  failure by the  Employee or the Company to set forth in the
Notice of Termination any fact or circumstance which contributes to a showing of
Good Reason or Cause shall not waive any right of the Employee or the Company


                                      E-3
<PAGE>

hereunder or preclude the  Employee or the Company from  asserting  such fact or
circumstance in enforcing the Employee's or the Company's rights hereunder.

2. OBLIGATIONS OF THE COMPANY UPON TERMINATION

     (a) If,  during the  Employment  Period,  the Company  shall  terminate the
Employee's  Full-Time  Employment  with the Company  other than for Cause or the
Employee  shall  terminate  his Full-Time  Employment  with the Company for Good
Reason:

          (i) The Company  shall pay to the Employee,  as severance,  Employee's
     Annual Base Salary in effect as of the Date of Termination.  Such severance
     payment  shall be made during the twelve (12) months  following the Date of
     Termination  in  accordance  with  the  Company's   standard   payroll  and
     withholding practice.

          (ii) As  severance,  Employee will be entitled to  participate  in the
     bonus pool which may be awarded to the officers of the Company for the year
     in which such termination  occurs (and any prior year with respect to which
     a bonus was  awarded  to  Employee  but not paid) to the same  extent as if
     Employee's  Full-Time Employment with the Company had not terminated during
     the year for which the bonus is  awarded;  provided  that the amount of the
     bonus  awarded to  Employee  will be pro rated  based on the number of days
     during  such year on which  Employee  was  employed  with the  Company on a
     Full-Time basis. For example, if Employee's  Full-Time  Employment with the
     Company  covers  six  months of the year for which the bonus is  awarded he
     would  receive  50% of the bonus he would have been  entitled to receive if
     his  Full-Time  Employment  with the Company  had covered the entire  year.
     Nothing  contained  herein shall  guarantee  that any bonus will be paid to
     Employee and Employee will only receive a bonus as determined  hereunder if
     the other officers of the Company are awarded a bonus.

          (iii) Effective as of the Date of  Termination,  the Company agrees to
     provide Employee,  and any spouse and/or  dependents  receiving medical and
     dental  coverage  on the  Date of  Termination  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,  29 U.S.C.  ss.ss.  1161-1168;  26 U.S.C.  ss.
     4980B(f),   as  amended,  and  all  applicable   regulations  (referred  to
     collectively as "COBRA"). The Company will reimburse Employee for the total
     applicable  premium  cost for the  medical  and dental  COBRA  continuation
     coverage elected for Employee and his or her Family Members for a period of
     up to  twelve  (12)  months  commencing  on the Date of  Termination.  Such
     reimbursements shall be subject to all applicable taxes,  including but not
     limited to state and federal income and employment taxes.

          (iv) In the event Employee obtains Full-Time  Employment within twelve
     (12)  months  of the Date of  Termination  with an  entity  other  than the
     Company,  and Employee and his or her Family Members become  eligible for a
     group health plan of such entity providing  medical and/or dental coverage,
     the  Company's  obligation to reimburse  Employee for the total  applicable
     premium  cost of medical and dental  continuation  coverage  elected  shall
     cease as of the date  such  coverage  for  Employee  and his or her  Family
     Members under such group health plan becomes effective.


                                      E-4
<PAGE>

          (v) For purposes of the Company's  Non-Qualified Stock Option Plan and
     determining the vesting of options granted to Employee under such Plan, the
     Compensation  Committee  has  determined  that Employee will continue to be
     deemed to be an employee of the Company during the period in which he works
     for the Company as a part-time  employee or makes himself available to work
     for the  Company  as a  part-time  employee  pursuant  to Section 3 hereof,
     provided  that if  Employee  refuses  or fails to  provide  such  part-time
     services,  or if  Employee  accepts  Full-Time  Employment  with any  other
     employer  during such period,  or if Employee  dies during such period,  he
     will no longer be deemed to be an employee of the Company for such purposes
     as of the date he refuses or fails to provide such part-time  services,  or
     the date he commences such Full-Time Employment, or the date he dies.

          (vi) In the event that Employee dies after  becoming fully entitled to
     the severance  payments  provided in section  2(a)(i) hereof but before the
     Employee  actually  receives all of such  payments,  any  remaining  unpaid
     payments will be made first to the Employee's surviving spouse, if any, and
     if there is no surviving  spouse,  to the Employee's  estate.  In the event
     Employee dies after becoming  entitled to the benefits  provided in section
     2(a)(iii) hereof, the Company shall continue to reimburse Employee's Family
     Members for the premium cost for COBRA  continuation  coverage  through the
     date which is twelve (12) months from the Date of Termination.

          (vii)  [Hardman  only:  The  Company  shall  waive,  in  writing,  the
     obligation  of Employee  pursuant to the letter  dated  ________,  from the
     Company to Employee,  to reimburse the Company for relocation costs paid by
     the Company on behalf of Employee in the amount of [_____________.]

     (b) This  Agreement  is  unfunded.  No fund is being set aside or allocated
specifically for the purpose of this Agreement.  All severance payments shall be
paid out of the  general  assets  of the  Company.  Employee  shall 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 severance payments.

     (c) No compensation  or benefits shall be payable to Employer  hereunder in
the event  Employee's  employment  with the Company is terminated for any reason
after  the  Employment  Period or in the event  Employee's  employment  with the
Company is  terminated  for Cause during the  Employment  Period or in the event
Employee  voluntarily  terminates his employment with the Company other than for
Good  Reason  during  the  Employment  Period.  In the  event  Employee  accepts
Full-Time  Employment  with an employer other than the Company during the twelve
(12) months  following the Date of  Termination,  Employee shall promptly notify
the  Company  that he has  accepted  such  Full-Time  Employment  and advise the
Company of the  anticipated  commencement  date for such  Full-Time  Employment.
Employee  shall no longer be  entitled  to receive  compensation  payable  under
section 2(a)(i) hereof as of the date Employee  commences  Full-Time  Employment
with such new employer.

3. OBLIGATIONS OF THE EMPLOYEE UPON TERMINATION

     (a) In the event the Company  terminates  Employee's  Full-Time  Employment
other than for Cause during the  Employment  Period or Employee  terminates  his
Full-Time  Employment  with the Company for Good  Reason  during the  Employment
Period,  Employee  will


                                      E-5
<PAGE>

continue  to work up to five (5) hours per month for the  Company as a part-time
employee as requested by the Company for a period of one (1) year  following the
Date of Termination.

     (b)  Employee may perform the  part-time  employment  required  pursuant to
Section 3(a) hereof 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.

4. NONCOMPETITION AND CONFIDENTIALITY

     (a) The "Noncompete Period" shall commence upon execution of this Agreement
and  continue  through  the date which is one year  following  the date on which
Employee's  Full-Time  Employment with the Company terminates.  In consideration
for  the  benefits  provided  to  Employee  under  this  Agreement,  during  the
Noncompete  Period,  Employee 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"),  (y)  developing,   marketing  or  selling
single-chain  antigen-binding proteins or (z) any technology or area of business
in which the Company becomes involved to a significant degree during the term of
Employee's 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, Employee
shall  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 Section 4(a) 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 Section 4(a) if such
research  project is not  material  to such  entity and  Employee  would have no
direct involvement in such research project;  provided in the case of employment
covered by clauses (ii) and (iii)  Employee shall have provided 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.  Employee is 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 Employee is employed by the
Company.  The provision  contained in the preceding  sentence  shall survive the
termination  of Employee's  employment  with the Company.  In the event Employee
breaches any of the covenants set forth in this Section 4(a), the running of the
period  of  restriction  set  forth  herein  shall  recommence  upon  Employee's
compliance  with the terms of this  Section  4(a).  Notwithstanding  the  above,
ownership by the Employee, 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 shall not constitute a breach
of this Section 4(a).


                                      E-6
<PAGE>

     (b) Employee  recognizes and acknowledges 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,  shall be and remain the sole and exclusive
property  of the Company  and is a  valuable,  special  and unique  asset of the
Company's  business.  The  Employee  will  not,  during or after the term of his
employment  by the  Company,  disclose  any  such  information  to  any  person,
corporation,  firm,  partnership  or  other  entity;  provided,  however,  that,
notwithstanding  the  foregoing,   during  the  term  of  Employee's   Full-Time
Employment  with  the  Company,  Employee  may  make  such  disclosure  if  such
disclosure is in the Company's best  interests,  is made in order to promote and
enhance the Company's  business,  and sufficient  arrangements are made with the
person or entity to whom such  disclosure is made to ensure the  confidentiality
of such  disclosure.  The  provisions  of this  Section  4(b) shall  survive the
termination of Employee's employment with the Company.

     (c) Employee  agrees that the  covenants and  agreements  contained in this
Section 4 are the  essence of 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 Employee  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  shall 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 shall 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  Employee  of any  such  covenants  or  agreements.
Notwithstanding  anything  herein to the contrary,  if a period of time or other
restriction  specified in this Section 4 should be determined to be unreasonable
in a judicial proceeding,  then the period of time or other restriction shall be
revised so that the covenants contained in this Section 4 may be enforced during
such period of time and in  accordance  with such other  restrictions  as may be
determined to be reasonable.

     (d)  Employee  agrees to assign and does  hereby  assign to the Company all
tangible and intangible  property,  including,  but not limited to,  inventions,
developments or discoveries conceived,  made or discovered by Employee solely or
in collaboration  with others during the term of Employee's  employment with the
Company, which relate in any manner to the Company's business.

5. NONEXCLUSIVITY OF RIGHTS

     Nothing in this Agreement shall prevent or limit the Employee's  continuing
or future participation in any plan, program, policy or practice provided by the
Company and for which the Employee may qualify,  nor shall anything herein limit
or  otherwise  affect such rights as the Employee may have under any contract or
agreement  with the  Company.  Amounts  which are vested  benefits  or which the
Employee is otherwise  entitled to receive under any plan,  policy,


                                      E-7
<PAGE>

practice  or program of or any  contract  or  agreement  with the  Company at or
subsequent to the Date of Termination  shall be payable in accordance  with such
plan, policy,  practice or program or contract or agreement except as explicitly
modified by this Agreement.

6. FULL SETTLEMENT; DETERMINATIONS; RESOLUTION OF DISPUTES

     (a) The  Company's  obligation  to make the  payments  provided for in this
Agreement  and  otherwise  to perform  its  obligations  hereunder  shall not be
affected by any set-off, counterclaim, recoupment, defense or other claim, right
or action which the Company may have against the Employee or others. In no event
shall the  Employee  be  obligated  to seek other  employment  or take any other
action by way of mitigation of the amounts  payable to the Employee under any of
the provisions of this  Agreement and such amounts shall not be reduced  whether
or not the Employee obtains other  employment,  except as otherwise  provided in
this  Agreement.  The Company  agrees to pay promptly upon invoice,  to the full
extent  permitted  by law,  all legal fees and  expenses  which the Employee may
incur as a result of any contest by the Company or the  Employee of the validity
or enforceability of, or liability under, any provision of this Agreement or any
guarantee of  performance  thereof  (including as a result of any contest by the
Employee concerning the amount of any payment pursuant to this Agreement) in the
event Employee shall prevail to a substantial extent in such contest action.

     (b) The following  claims  procedure shall be the claims  procedure for the
resolution of disputes and disposition of claims arising under this Agreement:

          (i) The  Employee or  beneficiary  of the  Employee  may file with the
     Company a written  request for benefits  under this Agreement in a form and
     manner prescribed by the Company.  Within thirty (30) days after the filing
     of such request,  the Company shall notify the claimant in writing  whether
     the  request is upheld or denied,  in whole or in part.  If the  request is
     denied,  in whole or in part,  the Company shall state in writing:  (i) the
     specific  reasons  for the  denial;  (ii) the  specific  references  to the
     pertinent  provisions of this Agreement on which the denial is based; (iii)
     a description of any additional  material or information  necessary for the
     claimant to perfect the claim and an  explanation  of why such  material or
     information  is  necessary;  and (iv) an  explanation  of the claims review
     procedure set forth herein.

          (ii)  Within  sixty  (60) days after  receipt  of an  initial  benefit
     determination in which benefits have been denied,  in whole or in part, the
     claimant may file with the Company a written  request for a review and may,
     in conjunction therewith, submit written issues and comments. Within thirty
     (30) days after the request for review was filed,  the Company shall make a
     decision on the  request  for review and notify the  claimant in writing of
     the Company's decision.

     (c) If there shall be any dispute  between the Company and the Employee (i)
in the event of any  termination of the Employee's  Full-Time  Employment by the
Company,  whether such  termination  was for Cause,  or (ii) in the event of any
termination  of  Full-Time  Employment  by the  Employee,  whether  Good  Reason
existed,  then, unless and until there is a final,  nonappealable  judgment by a
court of competent jurisdiction declaring that such termination was for Cause or
that the  determination  by the Employee of the existence of Good Reason was not
made in good faith, the Company shall pay all amounts, and provide all benefits,
to the


                                      E-8
<PAGE>

Employee and/or the Employee's  family or other  beneficiaries,  as the case may
be, that the Company  would be required to pay or provide  pursuant to Section 2
hereof as though such  termination  were by the Company  without Cause or by the
Employee  with Good Reason;  provided,  however,  that the Company  shall not be
required to pay any  disputed  amounts  pursuant to this  paragraph  except upon
receipt of an undertaking  satisfactory  in form and substance to the Company by
or on behalf of the  Employee to repay to the Company all such  amounts to which
the Employee is ultimately adjudged by such court not to be entitled.

7. SUCCESSORS

     (a) This  Agreement  is  personal  to the  Employee  and  without the prior
written consent of the Company shall not be assignable by the Employee otherwise
than by will or the laws of descent and distribution. This Agreement shall inure
to the benefit of and be enforceable by the Employee's legal representatives.

     (b) This  Agreement  shall inure to the benefit of and be binding  upon the
Company and its successors and assigns.

     (c) The Company will require any successor (whether direct or indirect,  by
purchase, merger, consolidation or otherwise) to all or substantially all of the
business  and/or assets of the Company to assume  expressly and agree to perform
this  Agreement in the same manner and to the same extent that the Company would
be required to perform it if no such succession had taken place. As used in this
Agreement,  "Company"  shall mean the  Company as  hereinbefore  defined and any
successor to its business and/or assets as aforesaid which assumes and agrees to
perform this Agreement by operation of law, or otherwise.

8. MISCELLANEOUS

     (a)  This  Agreement  shall,  except  to the  extent  that  federal  law is
controlling,  be governed by and  construed in  accordance  with the laws of the
State of New Jersey,  without  reference to principles of conflict of laws.  The
captions of this Agreement are not part of the provisions  hereof and shall have
no force or effect. This Agreement may not be amended or modified otherwise than
by a written  agreement  executed  by the  parties  hereto  or their  respective
successors and legal representatives.

     (b) All notices and other communications  hereunder shall be in writing and
shall be given by hand delivery to the other party or by registered or certified
mail, return receipt requested, postage prepaid, addressed as follows:

     If to the Employee:

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

     If to the Company:

     Enzon, Inc.


                                      E-9
<PAGE>

     20 Kingsbridge Road
     Piscataway, New Jersey 08854
     Attention: Corporate Secretary

     with a copy to:

     Dorsey & Whitney, LLP
     250 Park Avenue
     New York, NY 10177
     Attention: Kevin Collins

or to such other  address as either  party shall have  furnished to the other in
writing in accordance  herewith.  Notice and  communications  shall be effective
when actually received by the addressee.

     (c) The invalidity or  unenforceability  of any provision of this Agreement
shall not affect the validity or  enforceability  of any other provision of this
Agreement.

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

     (e)  The  Employee's  or  the  Company's  failure  to  insist  upon  strict
compliance with any provision hereof or any other provision of this Agreement or
the failure to assert any right the Employee or the Company may have  hereunder,
shall  not be  deemed  to be a waiver  of such  provision  or right or any other
provision or right of this Agreement.

     (f) The Employee and the Company  acknowledge that, except as may otherwise
be provided  under any other  written  agreement  between the  Employee  and the
Company, the employment of the Employee by the Company is "at will" and, subject
to the terms of this Agreement,  may be terminated by either the Employee or the
Company at any time.

     (g) This Agreement  contains the complete agreement between the parties and
supersedes any prior understandings, agreements or representations by or between
the  parties,  written or oral,  which may have  related to the  subject  matter
hereof  in any way,  including,  without  limitation,  the  Employee's  Secrecy,
Invention Assignment, and Non-Competition Agreement, executed by the Employee on
__________.

     (h)  This  Agreement  may  be  executed  in  counterpart,   each  of  which
counterpart  shall  be  deemed  an  original,  but all of which  together  shall
constitute one and the same instrument.


                                      E-10
<PAGE>

     IN WITNESS WHEREOF, the Employee has hereunto set his hand and, pursuant to
the  authorization  from its Board of  Directors,  the  Company  has caused this
Agreement  to be executed in its name on its behalf,  all as of the day and year
first above written.

                                ENZON, INC.

                                By:
                                    ---------------------------------------
                                    Name: Kenneth J. Zuerblis
                                    Title:  Vice President, Finance, Chief
                                    Financial Officer and Secretary


                                EMPLOYEE


                                -------------------------------------------
                                Name: [         ]


                                      E-11
<PAGE>

                                    Schedule

The  following  individuals  entered into an  agreement  with Enzon on August 3,
2001, substantially similar to the attached:

Norman Hardman
Josef Bossart
Kenneth Zuerblis
Jeffrey McGuire
Christopher Phillips


                                      E-12