During the past three years, from terminals within Beth Israel Hospital, Boston, 3,654 persons used a computer program called PaperChase to search the medical literature. While performing 39,022 searches, these persons had 1,976,421 references displayed and selected 449,690 of them for printing. Throughout this period, the program underwent continual modification. Each year the number of searches increased--from 10,678 to 11,541 to 16,803. Each year the percentage of new users who were unsuccessful decreased--from 16 to 13 to 11. By the end of the third year, 549 people had completed 20 or more searches. PaperChase enables people to search the medical literature themselves, and thus provides a new experience in computerized bibliographic retrieval. When made available without charge in a teaching hospital, PaperChase is widely used.