Business Wire - March 23, 2004

"We have seen some good results with our HIV compounds and are continuing to pursue this program," said Dr. Amit Kumar, President and CEO of CombiMatrix. "We look forward to expanding our relationship with Dr. Clotet to include testing of our siRNA pools for hepatitis C."

"The Hepatitis C and HIV viruses are two of the most deadly and prevalent viruses of our times," said Professor Bonaventura Clotet, M.D., Ph.D. "We see a growing population of co-infected patients whose morbidity and mortality are significantly increased through synergistic interactions of this combination. We hope our collaboration with CombiMatrix will position CombiMatrix to identify drug targets that will someday eradicate these deadly viruses."

It is estimated that over 4.5 million Americans and over 200 million people worldwide have been infected with hepatitis C. More than 80% develop chronic infections that lead to liver disease. Viral hepatitis C and HIV/AIDS are infectious diseases that are transmitted in many of the same ways and have drastic, long-term medical, economic, and social consequences for those infected with either or both viruses. About one quarter of HIV-infected persons in the United States are also infected with the hepatitis C.

About Retrovirology Laboratory irsiCaixa

The irsiCaixa Foundation is a leading institute and reference center for the research and treatment of Acquired Immuno Deficiency Syndrome (AIDS) in Europe. The Foundation was founded in 1995 with the objectives of advocating, inspiring and spreading medical investigation on (AIDS). The irsiCaixa Foundation Scientific Committee includes many world-renowned experts in the field of HIV research (www.irsicaixa.org/english/about/a_stru.html#comite).

The activity of the irsiCaixa Foundation is mainly carried out in the Retrovirology Laboratory of the University Hospital Germans Trias i Pujol in Badalona (Barcelona, Spain). The laboratory director is Dr. Bonaventura Clotet, chief of the AIDS unit of the University Hospital. Dr. Clotet received his M.D. of Medicine and Surgery at the Universitat Autonoma de Barcelona, in 1976. He earned his Ph.D. in the investigation of surrogate markers for connective tissue diseases in 1981.

Dr. Clotet has published more than 150 peer-reviewed papers. He is on the Editorial Board of the AIDS Journal and the Journal of the International Association of Physicians in AIDS Care. He has also authored numerous books and chapters on retrovirology and is an expert on siRNA and AIDS.

Professor Clotet is part of the organizing committees of several drug resistance workshops and International Conferences on AIDS, and he is an active member of the Expert Commission for the evaluation of research projects in the National Programme of Health and National AIDS Programme. Dr. Clotet was a co-chair of the Barcelona World AIDS meeting 2002. Information about the irsiCaixa Foundation is available at www.irsicaixa.org.

About Acacia Research Coporation

Acacia Research Corporation comprises two operating groups: Acacia Technologies Group and CombiMatrix Group.

The CombiMatrix group is developing a platform technology to rapidly produce customizable active biochips, which are semiconductor-based tools for use in identifying and determining the roles of genes, gene mutations and proteins. CombiMatrix's technology has a wide range of applications including DNA synthesis/diagnostics, siRNA synthesis, drug discovery, and immunochemical detection. CombiMatrix provides DNA arrays to researchers under the CustomArray(TM) brand. CombiMatrix's Express Track(sm) drug discovery program is a systems biology approach, using its technology, to target common viral diseases with siRNA compounds.

The Acacia Technologies Group develops, acquires, and licenses patented technologies. Acacia's DMT technology, which is supported by 5 U.S. and 31 foreign patents, relates to audio and audio/video transmission and receiving systems commonly known as audio-on-demand, video-on-demand, and audio/video streaming, and is used for distributing digital content via several means including Internet, cable, satellite and wireless systems.

Acacia Research-Acacia Technologies and Acacia Research-CombiMatrix (Nasdaq:CBMX) are both classes of common stock issued by Acacia Research Corporation and are intended to reflect the performance of the respective operating groups and are not issued by the operating groups.

Information about the Acacia Technologies Group and the CombiMatrix Group is available at www.acaciaresearch.com.

Safe Harbor Statement under the Private Securities Litigation Reform Act of 1995:

This news release contains forward-looking statements within the meaning of the "safe harbor" provisions of the Private Securities Litigation Reform Act of 1995. These statements are based upon our current expectations and speak only as of the date hereof. Our actual results may differ materially and adversely from those expressed in any forward-looking statements as a result of various factors and uncertainties, including the economic slowdown affecting technology companies, our ability to successfully develop products, rapid technological change in our markets, changes in demand for our future products, legislative, regulatory and competitive developments and general economic conditions. Our Annual Report on Form 10-K, recent and forthcoming Quarterly Reports on Form 10-Q, recent Current Reports on Forms 8-K and 8-K/A, and other SEC filings discuss some of the important risk factors that may affect our business, results of operations and financial condition. We undertake no obligation to revise or update publicly any forward-looking statements for any reason.

CONTACT: Acacia Research Corporation

Bret L. Undem (Media Relations), 425-493-2293

Fax: 425-493-2010

SOURCE: Acacia Research Corporation

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