XOMA Announces May 10 Conference Call and Webcast Discussion of First Quarter 2007 Financial Results

BERKELEY, Calif., April 26, 2007 (PRIME NEWSWIRE) -- XOMA Ltd. (Nasdaq:XOMA) will issue a news release announcing its first quarter financial results for the quarter ended March 31, 2007 on Thursday, May 10, 2007 after the close of the financial markets. The news release will be followed by a conference call and live webcast on Thursday, May 10, 2007 at 5:00 p.m. Eastern (2:00 p.m. Pacific) with XOMA management discussing first quarter financial results and providing a general business update. There will be a question and answer session at the end of the conference call.

The webcast can be accessed via XOMA's website at http://www.xoma.com and will be archived on the site and available for replay until close of business on August 08, 2007. To obtain phone access to the live audiocast in the U.S. and Canada, dial 1-877-407-9205. International callers should dial 1-201-689-8054. No conference ID is necessary. An audio replay will be available beginning two hours following the conclusion of the webcast through 11:59 pm Eastern (8:59 pm Pacific) on May 24, 2006. Access numbers for the replay are 1-877-660-6853 (U.S./Canada) or 1-201-612-7415 (International). Two access numbers are required for the replay: account number 286 and conference ID # 237414.

About XOMA

XOMA is a leader in the discovery, development and manufacture of therapeutic antibodies, with a therapeutic focus that includes cancer and immune diseases. XOMA has royalty interests in RAPTIVA(r) (efalizumab), a monoclonal antibody product marketed worldwide (by Genentech, Inc. and Merck Serono S.A.) to treat moderate-to-severe plaque psoriasis, and LUCENTIS(r) (ranibizumab injection), a monoclonal antibody product marketed worldwide (by Genentech and Novartis AG) to treat neovascular (wet) age-related macular degeneration.

The company has built a premier antibody discovery and development platform that includes access to seven of the leading commercially available antibody phage display libraries and XOMA's proprietary HE(tm) and BCE technologies. More than 45 companies have signed BCE licenses. XOMA's development collaborators include Lexicon Pharmaceuticals, Inc., Novartis, Schering-Plough Research Institute and Takeda Pharmaceutical Company Limited. With a fully integrated product development infrastructure, XOMA's product development capabilities extend from preclinical sciences to product launch. For more information, please visit the company's website at www.xoma.com.

Certain statements contained herein concerning current collaborations and product development, or that otherwise relate to future periods, are forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. These statements are based on assumptions that may not prove accurate. Actual results could differ materially from those anticipated due to certain risks inherent in the biotechnology industry and for companies engaged in the development of new products in a regulated market. These risks, including those related to the results of pre-clinical testing, the timing or results of pending and future clinical trials (including the design and progress of clinical trials; safety and efficacy of the products being tested; action, inaction or delay by the FDA, European or other regulators or their advisory bodies; and analysis or interpretation by, or submission to, these entities or others of scientific data), changes in the status of the existing collaborative relationships, the ability of collaborators and other partners to meet their obligations, market demand for products, scale up and marketing capabilities, competition, uncertainties regarding the status of biotechnology patents, uncertainties as to the cost of protecting intellectual property and risks associated with XOMA's status as a Bermuda company, are described in more detail in the Company's most recent annual report on Form 10-K and in other SEC filings. Consider such risks carefully in considering XOMA's prospects.

CONTACT:  XOMA Ltd.
          J. David Boyle II, Vice President Finance, Chief Financial Officer
          (510) 204-7200
          investorrelations@xoma.com
          www.xoma.com

Released April 26, 2007