SecProbe.io

September 21, 2010
 Steven B. Engle Chairman, Chief Executive Officer and President XOMA Ltd. 2910 Seventh Street Berkeley, California 94710
 Re: XOMA Ltd.
 Form 10-K for the Fiscal Year Ended December 31, 2009
  Filed March 11, 2010
  Form 10-K/A filed April 30, 2010   File No. 000-14710

 Dear Mr. Engle:

We have reviewed your filings and have the following comments.  In some of our
comments, we may ask you to provide us with  information so we may better understand your
disclosure.   Please respond to this letter within ten business days by providing the requested
information or by advising us when you will provide the requested response.  If you do not believe our comments apply to your facts and circumstances please tell us why in your
response.    After reviewing the information you provide  in response to these comments, we may
have additional comments.

Form 10-K for the fiscal year ended December 31, 2009
 Item 1. Business, page 1

 General

1. We note your discussion throughout  the Business section of various material license
and collaboration agreements with third partie s.  Please provide draft disclosure to be
included in an amended Form 10-K quan tifying the total potential milestone
payments due under each agreement to the extent not already di sclosed, a range of
royalties to be paid within a ten percen t range, and the duration and termination
provisions of each.
Signatures, page 71

2. We note that your chief executive officer a nd chief financial officer have signed the
Form 10-K on behalf of the registrant a nd in their own capacities, but it does not
appear that the filing has not been signed by your cont roller or principal accounting

Steven B. Engle
XOMA Ltd. September 21, 2010
Page 2
officer in those capacities as required by Form 10-K.  Please ensure that your
amendment to the Form 10-K includes the signature of the person acting in such
capacity, as required by Instructi on D.2(a) of Form 10-K.
 Form 10-K/A filed April 30, 2010

 Compensation Components, page 5

3. We note your disclosure regarding your long- term incentive program on page 5 of the
filing.  Please provide draft disclosure to  be included in an amended Form 10-K
discussing the actual award made to each na med executive officer for the 2009 fiscal
year and the conclusions reached by the compensation committee in determining each
award.  For instance, you note the factor s considered by the committee.  Your
disclosure should discuss how each factor was evaluated or measured and how the
totality of the factors resulte d in the award made to each named executive officer.

4. We note your disclosure regarding th e CEO Incentive Compensation Plan and
Management Incentive Compensation Plan on pages 5 and 6 of the filing.  Please provide draft disclosure to be included in  an amended Form 10-K which discusses the
following information:
• the “discretionary” and “individual” objectiv es referenced in the first and fifth
paragraphs on page 6;
• the level of achievement of each objective;
• how such level of achievement translated  into the awards made to each named
executive officer on an individual basis;
• the amount of the target incentive co mpensation pool and how such pool was
adjusted at year-end to reflect the company’s performance in achieving its corporate objectives; and
• any other factors considered by the committee that impacted the amount of
incentive compensation awarded to  the named executive officers.

Compensation Risk Assessment, page 7

5. We note your disclosure in response to It em 402(s) of Regulation S-K on page 7 of
the filing.  Please describe the process you undertook to reach your conclusion and
provide an analysis supporting your dete rmination that your compensation policies
and practices are not reasonably likely to have a material adverse effect on the
company.
 Employment Contracts and Termination of Employment and Change of Control
Arrangements, page 14

6. We note that you have filed a form of empl oyment agreement as Exhibit 10.7 to the
filing.  Please also file each named executive officer’s executed employment
agreement as an exhibit to the filing.

Steven B. Engle
XOMA Ltd. September 21, 2010 Page 3
We urge all persons who are responsible for the accuracy and adequacy of the
disclosure in the filing to be certain that the filing includes the information the Securities
Exchange Act of 1934 and all applicable Exchan ge Act rules require.  Since the company and
its management are in possession of all facts relating to a co mpany’s disclosure, they are
responsible for the accuracy and adequacy of the disclosures they have made.

In responding to our comments, please provi de a written statement from the company
acknowledging that:
• the company is responsible for the adequacy  and accuracy of the disclosure in the
filing;
• staff comments or changes to disclosure  in response to staff comments do not
foreclose the Commission from taking any action with respect to the filing; and
• the company may not assert staff comments as a defense in any proceeding initiated
by the Commission or any person under the federal securities laws of the United States.

Please contact Laura Crotty at (202) 551- 3563 or myself at (2 02) 551-3715 with any
questions.

 Sincerely,

 Jeffrey P. Riedler  Assistant Director