SecProbe.io

Mail Stop 6010         January 3, 2008   Christopher J. Margolin, Esq. XOMA Ltd. 2910 Seventh Street Berkeley, CA  94710
Re: XOMA Ltd.
 Registration Statement on Form S-3
Filed December 26, 2007
 File Number 333-148342
Dear Mr. Margolin:

We have reviewed your filing and have the fo llowing comments.  Where indicated, we think
you should revise your document in response to this comment.  If you disagree, we will consider your
explanation as to why our comment is inapplicable or  a revision is unnecessary.  Please be as detailed
as necessary in your explanation.

Form S-3

1. Please file forms of your indentures as exhi bits to the registration statement prior to
requesting effectiveness.  As you may be aware, the Trust Indenture Act of 1939 requires that
an indenture be qualified at  the time of registration.

In addition, we issued comments under separa te cover on your Form 10-K annual report for
fiscal year ended December 31, 2006, and we will be monitoring your registration statement for
clearance of these comments.  All co mments will need to be fully resolved before we take final action
on the registration statement.
* * *

  We urge all persons who are responsible for th e accuracy and adequacy of the disclosure in
the filings reviewed by the staff to be certain that they have provided all information investors require for an informed decision.  Since the company and its management are in possession of all facts relating to a company’s disclosure, they are re sponsible for the accuracy and adequacy of the
disclosures they have made.

Christopher J. Margolin, Esq.
XOMA Ltd. January 3, 2008 Page 2
 Notwithstanding our comments, in the even t the company requests acceleration of the
effective date of the pending registration statement,  it should furnish a letter, at the time of such
request, acknowledging that:

• should the Commission or the staff, acting pursua nt to delegated authority, declare the filing
effective, it does not foreclose the Commission from taking any action with respect to the
filing;

• the action of the Commission or the staff, acting pursuant to delegated authority, in declaring
the filing effective, does not re lieve the company from its full responsibility for the adequacy
and accuracy of the disclosure in the filing; and

• the company may not assert this action as a defense in any proceeding initiated by the Commission or any person under the federal securities laws of the United States.
 In addition, please be advised th at the Division of Enforcement has access to all information
you provide to the staff of the Divi sion of Corporation Finance in c onnection with our review of your
filing or in response to our comments on your filing.   We will consider a written request for acceleration of the effective date of the registration statement as a confirmation of the fact that those requesting acceleration are aw are of their respective
responsibilities under the Securities Act of 1933 and the Securities Exchange Act of 1934 as they
relate to the proposed public offeri ng of the securities sp ecified in the above registration statement.
We will act on the request and, pursuant to delegate d authority, grant acceleration of the effective
date.    Please contact Rose Zukin at (202) 551-3239 or me at (202) 551-3710 with any questions.
        S i n c e r e l y ,

        J e f f r e y  P .  R i e d l e r         A s s i s t a n t  D i r e c t o r    cc: Geoffrey E. Liebmann, Esq.  Cahill Gordon & Reindel LLP  80 Pine Street  New York, NY 10005