WITNESSETH

                      FOURTH AMENDMENT TO LICENSE AGREEMENT


     This Fourth Amendment to License Agreement (hereinafter "Amendment") is
made on December 23, 1998, to be effective as set forth herein, by and between
XOMA CORPORATION, a corporation organized and existing under the laws of the
State of Delaware and having a place of business at 0000 Xxxxxxx Xxxxxx,
Xxxxxxxx, Xxxxxxxxxx 00000 (hereinafter "CORPORATION"), and NEW YORK UNIVERSITY,
a corporation organized and existing under the laws of the State of New York and
having a place of business at 00 Xxxxxxxxxx Xxxxxx Xxxxx, Xxx Xxxx, Xxx Xxxx
00000 (hereinafter "NYU").

                                   WITNESSETH

     WHEREAS, CORPORATION and NYU entered into a certain agreement made and
effective as of August 6, 1990, as amended and restated on September 1, 1993 and
as subsequently amended on August 1, 1996 and June 12, 1997 (as so amended and
restated, the "Agreement"), pursuant to which, inter alia, CORPORATION undertook
to sponsor the NYU Research Project (as such term is defined in the Agreement)
and NYU granted to CORPORATION the License (as such term is defined in the
Agreement); and

     WHEREAS, CORPORATION and NYU wish to amend the Agreement as specified
herein;


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     NOW, THEREFORE, in consideration of the premises and the covenants,
conditions and promises set forth below, the parties hereto hereby agree as
follows:

     1.   Except as expressly provided for herein, all terms and conditions of
          the Agreement shall remain in full force and effect.

     2.   Terms which are defined in the Agreement shall have the same meanings
          when used in this Amendment, unless a different definition is given
          herein.

     3.   Section 18.a.(ii) of the Agreement shall be, and hereby is, amended by
          deleting the word "and" at the end thereof.

     4.   Section 18.a of the Agreement shall be, and hereby is, amended by
          adding a semicolon and the following language after the word
          "Agreement" and before the period at the end thereof:

          iv)  CORPORATION is planning a corporate reorganization (the
               "Reorganization") whereby CORPORATION would change its legal
               domicile from Delaware to Bermuda. Notwithstanding the
               Reorganization, CORPORATION agrees to comply with the applicable
               provisions of the Xxxx-Xxxx Act of 1980 and the regulations
               promulgated thereunder including, without limitation, the
               requirement that any Licensed Products using the subject
               technology will be manufactured substantially in the United


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               States to the extent required by 35 U.S.C. ss. 204.

     5.   This Amendment shall be effective only upon consummation of the
          Reorganization.

     IN WITNESS WHEREOF, the parties hereto have executed this Amendment as
follows:

NEW YORK UNIVERSITY                                XOMA CORPORATION



By:  /s/ Xxxxx X. Xxxxxxxx                     By:  /s/ Xxxxxxxxxxx X. Xxxxxxxx
     ----------------------------                   ---------------------------
     Xxxxx X. Xxxxxxxx                              Xxxxxxxxxxx X. Xxxxxxxx
     Assistant Xxxx and Vice                        Vice President, General
     President for Industrial                       Counsel and Secretary
     Liaison