EISAI OBTAINS FAVORABLE RULING IN ACIPHEX® PATENT INFRINGEMENT LAWSUIT AGAINST TEVA PHARMACEUTICALS AND DR. REDDY'S LABORATORIES

Tokyo, Japan, May 12 and Woodcliff Lake, NJ, May 11, 2007 - Eisai Co., Ltd. and its U.S. subsidiary Eisai Inc. (collectively “Eisai”) today announced that the United States District Court for the Southern District of New York has ruled in Eisai's favor with respect to Eisai's patent infringement lawsuit against Teva Pharmaceuticals and Dr. Reddy's Laboratories concerning Aciphex® (generic name: rabeprazole sodium, Product Name in Japan: Pariet®).

As previously announced, Eisai filed the infringement actions in November 2003 contesting Teva Pharmaceuticals and Dr. Reddy's Laboratories' submissions of abbreviated new drug applications (ANDAs) to the FDA for Aciphex®. In October 2006, Judge Gerard E. Lynch of the United States District Court for the Southern District of New York granted partial summary judgment to Eisai, upholding the validity of the Aciphex® composition of matter patent.

In this subsequent ruling, Judge Lynch has also determined that Eisai's patent is enforceable. All issues in the case have been resolved, and final judgment will be entered in favor of Eisai.

“Throughout this process we were adamant that our Company's rabeprazole composition of matter patent is valid and enforceable until its expiration date on May 8, 2013. We are pleased with the Court's decision and will continue to actively protect our intellectual property throughout the world to ensure continued production of the highest quality products for the benefit of patients and their families,” said Mr. Hajime Shimizu, Chairman & CEO of Eisai Inc.

Aciphex® is classified as a proton pump inhibitor that effectively suppresses gastric acid secretion while inhibiting enzyme activity during the last phase of stomach acid secretion. Aciphex® was launched in the U.S. in 1999 and is currently marketed in more than 70 countries worldwide, including Japan, the U.K. and Germany. In the United States, Eisai Inc. copromotes Aciphex® with PriCara™, unit of Ortho-McNeil, Inc.

Eisai Co., Ltd. is a research-based human health care (hhc) company that discovers, develops and markets products throughout the world. Eisai's corporate human health care (hhc) mission is to give first thought to patients and their families, and to increase the benefits that health care provides. The company believes that increasing patient satisfaction through the development of innovative new medicines exemplifies its important mission. For more information about Eisai Co., Ltd., please visit www.eisai.co.jp/index-e.html.

Eisai Inc. is a U.S. pharmaceutical subsidiary of Eisai Co., Ltd. Established in 1995, Eisai Inc. began marketing its first product in the United States in 1997 and has rapidly grown to become an integrated pharmaceutical business with sales of approximately $2.2 billion in fiscal year 2005 (year ended March 31, 2006). For more information about Eisai Inc., please visit www.eisai.com.

Aciphex® has a well-established safety profile. The most common side effect possibly related to Aciphex® is headache. Symptom relief does not rule out other serious stomach conditions. Patients on warfarin (such as Coumadin®) may need to be monitored more closely by their doctor. For more information, visit www.aciphex.com or www.eisai.com.

This press release may contain so-called “forward-looking statements.” These statements are based on current expectations, forecasts and assumptions that are subject to risks and uncertainties which could cause actual outcomes and results to differ materially from these statements. Risks and uncertainties include general industry and market conditions, and general domestic and international economic conditions such as interest rate and currency exchange fluctuations. Risks and uncertainties particularly apply with respect to product-related forward-looking statements. Product risks and uncertainties include, but are not limited to, technological advances and patents attained by competitors; challenges inherent in new product development, including claims and concerns about product safety and efficacy; domestic and foreign healthcare reforms; trends toward managed care and healthcare cost containment; and governmental laws and regulations affecting domestic and foreign operations. Also, there are manufacturing and marketing risks and uncertainties, which include, but are not limited to, inability to build production capacity to meet demand, unavailability of raw materials, and failure to gain market acceptance. The Company disclaims any intention or obligation to update or revise any forward-looking statements whether as a result of new information, future events or otherwise.