The USSR medical information network includes 4,000 specialized libraries to serve 1.2 million physicians and 100,000 researchers and teachers. In 1988, NPO SOYUZMEDINFORM, an All-Union branch medical information center within the Ministry of Public Health, implemented a data base on Soviet medical literature. This data base indexes 85,000-100,000 documents from books, journals, conferences, dissertations, non-published materials, etc., to cover 95% of Soviet medical literature. Other services include catalog card production, weekly indexes, special bibliographies, SDI, on-line searching, and document deliveiy. The new data base uses the MeSH thesaurus as a replacement for the former Soviet indexing system to help integrate it into the international network of medical information. The steps for entering documents, the equipment used, and the outputs are also described.