ROCHE DIAGNOSTICS AND QUEST DIAGNOSTICS ESTABLISH BROAD-BASED ALLIANCE TO DEVELOP AND MARKET INNOVATIVE GENE-BASED MEDICAL TESTS

INDIANAPOLIS, IN AND TETERBORO, NJ (October 17, 2001) - Roche Diagnostics, a world leader in clinical diagnostic products and services and a pioneer in molecular diagnostics, and Quest Diagnostics Incorporated (NYSE: DGX), the nation's leader in gene-based medical testing with laboratories across the country, have entered into an alliance to develop and commercialize new gene-based medical tests and to expand access to gene-based testing for patients, physicians and hospitals. Financial terms of the agreement were not disclosed.

The gene-based tests will be based on Roche Diagnostics' patented polymerase chain reaction (PCR) technology, which is recognized as the gold standard for gene-based testing and an important enabling technology for applied genomics. Collaborations are expected to focus mainly on applications in pharmacogenomics and predictive medicine. Pharmacogenomics tests are used to predict the effectiveness of specific therapies in individuals and also to help physicians monitor the effectiveness of treatments. Predictive medicine tests are used by physicians to evaluate an individual's predisposition to diseases. In addition, the companies plan to collaborate on the commercialization of gene-based markers to assess an individual's risk for stroke and asthma. Some of these tests may originate through Roche Diagnostics' partnerships with other companies such as Affymetrix, Inc. and deCODE Genetics.

In addition to developing new tests, the companies agreed to expand the use of PCR technology in routine clinical laboratory tests, offering patients, physicians, and hospitals enhanced accuracy, reliability and speed. Quest Diagnostics is already utilizing the Roche COBAS AMPLICOR™ PCR platform for HIV testing. Under this agreement, Quest Diagnostics has also agreed to standardize current testing for Chlamydia trachomatis and Neisseria gonorrhea (CT/NG) on the Roche Diagnostics' AMPLICOR® PCR platform across all 30 Quest Diagnostics regional full-service laboratories. Potential future collaborations include evaluation of the next generation of assays for viral diseases such as hepatitis C virus (HCV) utilizing "real-time PCR" on Roche Diagnostics' COBAS TaqMan® platform. Such developments will expand the use of PCR technology in routine clinical laboratory tests.

"We are very excited about working with Quest Diagnostics to advance gene-based testing," said Martin Madaus, president and CEO of Roche Diagnostics Corporation. "By combining our experience and resources, we expect to expedite the transition of genomic discoveries into effective diagnostic products. This agreement reflects Roche Diagnostics' long-term commitment to expanding its involvement in human genetics research through both in-house activities and strategic alliances."

"Genomics has changed medicine forever, and it all starts with a diagnostic or predictive gene-based medical test," said Kenneth W. Freeman, chairman and CEO of Quest Diagnostics. "We are pleased to be collaborating with Roche Diagnostics, which developed PCR technology. Our clinical expertise combined with Roche Diagnostics' research capability will expand access to PCR technology for millions of patients and their physicians."

Quest Diagnostics, based in Teterboro, N.J., is the nation's leading provider of diagnostic testing, information and services with $3.4 billion in annual revenues. The company's diagnostic testing yields information that enables healthcare professionals and consumers to make better decisions to improve health. Quest Diagnostics offers patients and physicians the broadest access to diagnostic testing services through its national network of approximately 30 full-service laboratories, 150 rapid response laboratories and more than 1,300 patient service centers, where specimens are collected. Quest Diagnostics is the leading provider of esoteric testing, including gene-based testing, and is the leader in routine medical testing, drugs of abuse testing, and non-hospital-based anatomic pathology testing. Through partnerships with pharmaceutical, biotechnology and information technology companies, Quest Diagnostics provides support to help speed the development of healthcare insights and new therapeutics. Additional company information can be found on the Internet at: www.questdiagnostics.com.

Headquartered in Basel, Switzerland, Roche is one of the world's leading research-oriented healthcare groups in the fields of pharmaceuticals, diagnostics and vitamins. Roche's products and services address prevention, diagnosis and treatment of diseases, thus enhancing well-being and quality of life. Roche Diagnostics Division, the world leader in in-vitro diagnostics with a uniquely broad portfolio, supplies a wide array of innovative testing products and services to researchers, physicians, patients, hospitals and laboratories worldwide. Roche Diagnostics Corporation, based in Indianapolis, is the North American headquarters for the diagnostics business of the company.

The statements in this press release which are not historical facts or information may be forward-looking statements. These forward-looking statements involve risks and uncertainties that could cause the outcome to be materially different. Certain of these risks and uncertainties are listed in the Quest Diagnostics Incorporated 2000 Form 10-K and subsequent filings.

AMPLICOR and TAQMAN are trademarks of Roche Diagnostics, a member of the Roche Group.