"The Merck Manual" (17th [Centennial] Edition, 1999) is celebrating 100 years of providing quality medical information to healthcare professionals world-wide. Since 1899, "The Merck Manual" has set the standard for excellence in the medical community for current, complete, and comprehensive information on all areas of medicine. It is the oldest continuously published general medical text in the English language and the most widely used medical textbook in the world.