"The Medical and Health Related Sciences Thesaurus is the list of indexing terms developed and maintained as an integral component of CRISP (Computer Retrieval of Information on Scientific Projects), a comprehensive system furnishing scientific data on all research projects supported by the Public Health Services. CRISP is operated by the Research Documentation Section, Statistics and Analysis Branch, Division of Research Grants. The Thesaurus also comprises the vocabulary base for subject headings appearing in the annual Research Awards Index, a product of CRISP also produced by the Section. Documents used as source material for information entering the Thesaurus, CRISP and the Index represent current research projects for FY 1981 covering many widely diversified areas of medicine, dentistry, mental health, and allied public health fields. In order to maintain a vocabulary of terms which is both timely and representative of these changing and expanding research areas, constant revisions are being made. These revisions are reflected in updated editions of the Thesaurus published annually, As in the past, it is hoped that this revised edition will further aid the efforts of research analysts, information specialists, librarians and other individuals who have the responsibility for scientific communication systems."