This report on the multidisciplinary PASCAL database describes the files and the indexing rules for chemistry, biology, and medicine. PASCAL deals with all aspects of chemistry within two subfiles whose combined yearly growth is about 100,000 references. The Biopascal file, organized in the two subfiles of Plant Science and Biology and Medicine, presently contains 1,300,000 references and grows at a rate of 200,000 references annually. The primary sources for these files are the same as those for the whole PASCAL file and include serials, doctoral and master's theses, and patents. Principal languages covered are English, French, German, and Russian, with about 11 percent of the total in other languages. Indexing for chemistry uses two lexicons of controlled terms describing phenomena, processing, properties, methods, equipment, names of chemical reactions, and substructures or families of chemical compounds. A similar set of two vocabularies is used for biology and medicine. The form of the descriptors and the indexing is similar to that used throughout PASCAL in that indexing is accomplished to the most specific term within a hierarchical structure. Specific indexing rules are provided in detail for subdivisions within the three disciplines. (RAA)