This text provides a complete account of this particular rat strain. The book includes extensive data on reproductive indices, congenital abnormalities, growth, clinical signs, mortality, organ weights and chemical pathology. The data are derived from around 9000 control animals used in toxicology studies of two weeks to two years duration, completed between 1960 and 1992, and include 24 two-year studies and one life-span study of a 51 month duration. These extended periods of study have shown that many diseases are seen more frequently in later years.; Diseases are dealt with by body system and include clinical signs, macroscopic features and histopathology illustrations of the important or unusual diseases. Incidence levels are provided for all diseases and these are compared with published data for other rat strains.