FOR IMMEDIATE RELEASE

THOMSON CENTERWATCH PROVIDES GLOBAL CLINICAL TRIAL PROTOCOL REGISTRY AND RESULTS DATABASE FOR ROCHE

Global Transparency in Clinical Trial Information

BOSTON - April 15, 2005 - Thomson (TSX: TOC; NYSE: TOC), a global leader in providing integrated information solutions to scientific and healthcare customers, announced that its CenterWatch business entered into an agreement with Roche, one of the world’s leading research-focused groups in pharmaceutical and diagnostics. The agreement results in the transparent listing of Roche clinical trials information on two Web sites.

At www.centerwatch.com, physicians and patients can locate ongoing clinical trials that may be appropriate to their specific condition. This site also ensures healthcare providers and patients have timely access to clinical study results. At www.roche-trials.com, a Roche-branded site built by CenterWatch, Roche will publicize their trial protocol and results information. CenterWatch and Roche will launch the first release phase of www.roche-trials.com on April 15, 2005, while the registry and results database available at www.centerwatch.com will be released later this April.

Although the primary purpose of these online databases is to add transparency to clinical trials activities, the experts at CenterWatch foresee an added benefit of increased patient awareness and participation in trials. Patient participation continues to be a hurdle for academic and industry sponsors in completing a clinical trial within the pre-planned timelines, delaying the availability of optimized treatment regimens or new drugs on the market. Listing summaries of ongoing or active trial protocols online could help increase patient awareness and participation in the trials.

Including the complete Phase II – IV trial results through these online databases will help ensure these results contribute to scientific knowledge. For marketed medicines, these results also provide an important supplement to prescribing information and publications in scientific literature. The American Medical Association estimates medical journals publish less than half of all clinical trial results and the vast majority of published results are positive. “By working together, Roche and CenterWatch are addressing the issue of transparency. Regardless of a clinical trial’s outcome or where in the world the study was conducted, these free and global resources will list the facts for physicians and patients,” said Daniel McDonald, vice president of Thomson CenterWatch.

“This is a unique opportunity for Roche to provide physicians and patients with online access to important Phase II-IV trial information and offers us tremendous outreach opportunities to the healthcare community. We are excited to collaborate with CenterWatch, and hope this effort can be expanded to include trial information from other pharmaceutical companies in the future,” said Dr. Cheryl Karol, global director of Ethics in Clinical Research, Hoffmann-La Roche.

About The Thomson Corporation and CenterWatch
The Thomson Corporation (www.thomson.com), with 2004 revenues of over $8.10 billion, is a global leader in providing integrated information solutions to business and professional customers. Thomson provides value-added information, software tools, and applications to more than 20 million users in the fields of law, tax, accounting, financial services, higher education, reference information, corporate e-learning and assessment, scientific research, and healthcare. Its healthcare solutions include CenterWatch, (www.centerwatch.com), a leader in the clinical trials industry. With a specific focus on the clinical trials industry, CenterWatch is a Boston-based publishing and information services company that provides business journalism, reference databases, accredited training manuals, original research & analysis, and market intelligence services to assist organizations in managing and implementing clinical research strategies and operational initiatives. With operational headquarters in Stamford, Conn., Thomson has approximately 38,000 employees and provides services in approximately 130 countries. The Corporation's common shares are listed on the New York and Toronto stock exchanges (TSX: TOC; NYSE: TOC).

About Hoffmann-La Roche
Founded in 1896 and headquartered in Basel, Switzerland, Roche is one of the world's leading innovation-driven healthcare groups. Its core businesses are pharmaceuticals and diagnostics. Roche is one of the world's leaders in diagnostics, the leading supplier of pharmaceuticals for cancer, as well as a leader in virology and transplantation. As a supplier of products and services for the prevention, diagnosis and treatment of disease, the Group contributes on many fronts to improve people's health and quality of life. Roche employs roughly 65,000 people in 150 countries, including approximately 15,000 in the United States.

Roche's U.S. operations celebrate their American Centennial in 2005. In another milestone this year, Roche was named in January to Fortune magazine's list of Best Companies to Work for in America. One of an increasingly rare breed of major healthcare companies that still bear their original name, Roche today has more than a dozen U.S. sites located in California, Colorado, Indiana, New Jersey and South Carolina, as well as in Puerto Rico. Roche has alliances and research and development agreements with numerous partners, including majority ownership interests in Genentech and Chugai. Roche's Pharmaceuticals Division offers a portfolio of leading medicines in therapeutic areas including cancer, HIV/AIDS, hepatitis C, transplantation, dermatology and influenza. Roche's Diagnostics Division supplies a wide array of innovative testing products and services to researchers, physicians, patients, hospitals and laboratories world-wide. For further information, please visit our worldwide and U.S. websites (Global: www.roche.com and U.S.: www.roche.us).

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