Exhibit 10.1A


                                AMENDMENT TO THE
                                    XOMA LTD.
                             1981 SHARE OPTION PLAN



     Effective as of February 25, 2003, pursuant to Board action, the XOMA Ltd.
1981 Share Option Plan (the "Plan") is hereby amended as follows:

     1. Section 5(d) of the Plan is amended to read as follows:

     "(d) Effect of Termination of Employment.

          (1) Termination Generally. Should an optionee cease to be an employee
     of the Company while the holder of one or more outstanding options granted
     to such optionee under the Plan for any reason other than as provided under
     subsections (2), (3) or (4) below, then such option or options shall not
     remain exercisable (except as otherwise specifically authorized under
     Section 11) for more than a twelve (12) month period (or such shorter
     period as is determined by the Plan Administrator and set forth in the
     option agreement) following the date of such cessation of employee status,
     and each such option shall, during such twelve (12) month or shorter
     period, be exercisable only to the extent of the number of shares (if any)
     for which the option is exercisable on the date of such cessation of
     employee status. Under no circumstances, however, shall any such option be
     exercisable after the specified expiration date of the option term. Upon
     the expiration of such twelve (12) month or shorter period or (if earlier)
     upon the expiration of the option term, the option shall terminate and
     cease to be exercisable.

          (2) Termination on Death. Effective for options granted on or after
     March 11, 2003, should an optionee cease to be an employee of the Company
     while the holder of one or more outstanding options under the Plan by
     reason of death, then such option or options shall become fully exercisable
     on the date of death even if such options were not fully exercisable prior
     to death, and shall remain exercisable for a twelve (12) month period
     following the date of death. Under no circumstances, however, shall any
     such option be exercisable after the specified expiration date of the
     option term. Upon the expiration of such twelve (12) month period or (if
     earlier) upon the expiration of the option term, the option shall terminate
     and cease to be exercisable. In the case of any option granted to an
     optionee under the Plan and exercisable following the optionee's death,
     such options shall be exercisable by the personal representative of the
     optionee's estate or by the person or persons to whom the option is
     transferred pursuant to subsection (b) above, provided such exercise occurs
     prior to the earlier of (i) the expiration of a twelve (12) month period
     following the date of the optionee's death or (ii) the specified expiration
     date of the option term.



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          (3) Termination on Retirement. Effective for options granted on or
     after February 25, 2003, should an optionee cease to be an employee of the
     Company while the holder of one or more outstanding options under the Plan
     by reason of retirement at or after age fifty-five (55) and where the
     optionee's age plus years of full-time employment with the Company exceed
     seventy (70) ("Retirement"), then such option or options shall become fully
     exercisable as of the date of Retirement (even if such options were not
     fully exercisable prior to Retirement) and shall remain exercisable for the
     full option term as if the optionee had continued in employment. Upon the
     expiration of the option term, the option shall terminate and cease to be
     exercisable.

          (4) Termination for Cause or Unauthorized Disclosure. If (i) the
     optionee's status as an employee is terminated for cause (including, but
     not limited to, any act of dishonesty, willful misconduct, fraud or
     embezzlement or any unauthorized disclosure or use of confidential
     information or trade secrets) or (ii) the optionee makes or attempts to
     make any unauthorized use or disclosure of confidential information or
     trade secrets of the Company or its subsidiaries, then upon the occurrence
     of any such event all outstanding options granted the optionee under the
     Plan shall immediately terminate and cease to be exercisable.

          (5) Discretion to Accelerate Exercisability. Notwithstanding
     subsection (1) above, the Plan Administrator shall have the discretion to
     establish as a provision applicable to the exercise of one or more options
     granted under the Plan that during the period of exercisability following
     cessation of employee status (as provided in such subsections), the option
     may be exercised not only with respect to the number of shares for which it
     is exercisable at the time of the optionee's cessation of employee status
     but also with respect to one or more installments of purchasable shares for
     which the option otherwise would have become exercisable had such cessation
     of employee status not occurred.

          (6) Employment by Company or Subsidiary. For purposes of the foregoing
     provisions of this Section 5(d), the optionee shall be deemed to be an
     employee of the Company for so long as the optionee remains in the employ
     of the Company or one or more of its subsidiaries.

          (7) Consultant. If the option is granted to a consultant or other
     independent contractor, then the instrument evidencing the granted option
     shall include provisions comparable to subsections (1), (2), (3) and (4)
     above, and may include provisions comparable to subsection (5) above, with
     respect to the optionee's termination of service with the Company or its
     subsidiaries."





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