Exhibit 10.20

                                 ADDENDUM TO THE
                         EXECUTIVE EMPLOYMENT AGREEMENT
                               OF OCTOBER 9, 1995

This Addendum to the Executive Employment Agreement, originally dated October 9,
1995,  is executed  on May  __,2001,  to be  effective  on July 1, 2001,  by and
between  OXiGENE,  Inc. a Delaware  corporation with its principal office at 321
Arsenal  Street,  Watertown,  MA 02472 (the  "Company"),  and Bjorn  Nordenvall,
Ph.D.,  M.D.,  currently with a residence at 319 Marlborough,  Boston,  MA 02116
(the "Executive").  The parties to this Agreement are referred to, collectively,
as the "Parties".

Whereas,  the Parties  have  entered  into an  Executive  Employment  Agreement,
originally  dated October 9, 1995, and thereafter  amended,  of which the latest
amendment  is  dated  July 1,  1999  (as so  amended  to  date,  the  "Executive
Employment Agreement"); and.

Whereas, the Parties have agreed, taking into account the move of Executive from
Sweden to the United  States at the  request of the  Company and the role played
and  anticipated  by Executive  in the  Company's  success,  upon an increase in
Executive's  present  annual Base Salary of $225,000 to a new annual Base Salary
of $250,000 and the promise by the Company to Executive of a rent-free residence
and the use of an automobile in the Boston, Massachusetts, USA, area.

Now therefore the Parties agree as follows:

1.   The minimum annual Base Salary provided for in Section 2(a) ("Base Salary")
     of the  Executive  Employment  Agreement is hereby  amended to  $250,000.00
     (U.S.) per annum.

2.   The following shall be added to, and shall become and be a part of, Section
     4 ("Benefits") of the Executive Employment Agreement:

     (d)  Residence benefit.  The Company shall, during the period July 1, 2001,
          through and including June 30, 2002, make available to Executive,  for
          use by himself and his family,  a rent-free  residence  in the Boston,
          Massachusetts,  area on the terms herein set forth.  Pursuant  hereto,
          the  Company  shall  also bear the  expense of  electricity,  heating,
          water,  refuse  collection and other similar  expenses  related to the
          residence.  The  Executive  shall  approve a  residence  chosen by the
          Company,  and the Parties have  estimated  that the monthly rental due
          thereon shall be  approximately  $6,000.00  (excluding  other expenses
          associated with the expected occupancy and use of the premises).

     (e)  Car  benefit.  The  Company  shall,  during the  period  July 1, 2001,
          through and including June 30, 2002,  make  available  without cost to
          the Executive an automobile for use in connection  with his activities
          on behalf of the Company in the United States, and particularly in the
          Boston, Massachusetts, area. Pursuant hereto, the Company shall pay up
          to $600  per  month  for  the  cost of  usage  of the car and  related
          insurance.  Additionally,  the Company will pay for the lull operating
          costs  of  the  vehicle,   including  reasonable  fuel,   consumables,
          maintenance  and  repairs,  registration  and  licensing,  parking and
          tolls.

3.   The Parties hereto agree further that the provisions  hereinabove set forth
     shall be extended for an  additional  twelve month period if the  Executive
     Employment  Agreement  has not been  terminated on or before June 30, 2002,
     and the  Executive's  principal place of employment for the Company remains
     at the Company's principal office in the Boston, Massachusetts, area.

4.   This Addendum shall become  effective July 1, 2001, and, unless extended as
     set forth in Paragraph numbered 3 above, shall terminate on June 30, 2002.

5.   Except as set forth in this Addendum,  the Executive  Employment  Agreement
     and all prior  amendments  thereof and addenda  thereto  shall in all other
     respects be unchanged and remain in lull force and effect.


This  Addendum has been executed in two (2)  originals,  of which each Party has
retained one.

The Company                                          The Executive

OXiGENE, Inc.


/s/ Frederick Driscoll                               /s/ Bjorn Nordenvall
----------------------                               --------------------
    Frederick Driscoll                                   Bjorn Nordenvall