Merck Licenses IPA Application

IPA DEPLOYED BROADLY FOR USE BY MERCK SCIENTISTS WORLDWIDE

MOUNTAIN VIEW, CA and WHITEHOUSE STATION, NJ . December 6, 2004 Merck & Co., Inc. (NYSE: MRK) and Ingenuity announced today the license and deployment of the IPA application for use by Merck scientists worldwide. Under the terms of the multi-year agreement, Merck scientists will utilize Ingenuity’s software and extensive knowledgebase of biological networks and pathways curated from public literature. The IPA application will be used in synergy with Merck’s advanced Molecular Profiling tools, technologies and databases.

“We are pleased to be working with Ingenuity,” said Dr. Alan Sachs, vice president, Molecular Profiling, Merck Research Laboratories, and Site Head of Rosetta Inpharmatics, a wholly owned subsidiary of Merck. “Ingenuity’s application software and knowledgebase will provide Merck scientists with direct access to public and proprietary biological network data, and fits well with our overall mission of providing our scientists with the best information and tools to empower cutting edge pharmaceutical research.”

“IPA has potential for improving R&D productivity and we are excited about the opportunity to work with Merck for the broad deployment of IPA which supports our mutual goal of building and deploying a world class pathways capability for Merck scientists,” said Jake Leschly, chief executive officer of Ingenuity Systems.

IPA also will be integrated with Merck’s bioinformatics systems so that scientists may seamlessly traverse these applications, simplifying workflow and streamlining genomic and proteomic analysis.

About Merck & Co., Inc

Merck is a leading research-driven pharmaceutical company. Merck discovers, develops, manufactures and markets a broad range of innovative products to improve human and animal health, directly and through its joint ventures.

About Ingenuity Systems

Ingenuity Systems is helping life science researchers explore and understand biological systems that are foundational to human health and disease. Ingenuity delivers capabilities and expertise to researchers through analysis software, genome-scale computable network databases, and knowledge management services and infrastructure, resulting in increased productivity and faster drugs to market. The company was founded in 1998 and is headquartered in Mountain View, California.www.ingenuity.com.

Merck & Co., Inc.’s Forward-Looking Statement

This press release contains “forward-looking statements” as that term is defined in the Private Securities Litigation Reform Act of 1995. These statements involve risks and uncertainties, which may cause results to differ materially from those set forth in the statements. The forward-looking statements may include statements regarding product development, product potential or financial performance. No forward-looking statement can be guaranteed, and actual results may differ materially from those projected. Merck undertakes no obligation to publicly update any forward-looking statement, whether as a result of new information, future events, or otherwise. Forward-looking statements in this press release should be evaluated together with the many uncertainties that affect Merck’s business, particularly those mentioned in the cautionary statements in Item 1 of Merck.s Form 10-K for the year ended Dec. 31, 2003, and in its periodic reports on Form 10-Q and Form 8-K (if any) which the company incorporates by reference.