Seven years ago physicians at the Beth Israel Hospital in Boston began doing their own searches of the medical literature. They used PaperChase, a computer program written especially for end users rather than for search librarians. The data base was initially limited to the journals shelved in the library of the Beth Israel Hospital, but it has since been expanded to include the entire MEDLINE collection of the National Library of Medicine-nearly 5 million references published in 3,400 biomedical journals dating back to 1966.PaperChase is now available throughout the United States and Canada to anyone who has a computer terminal or personal computer and a modem. No special training is needed for a successful search and there is no user's manual. Users can search by title word, "medical subject heading," author's name, journal title, year of publication, language of publication or any combination of the above. They can read abstracts on line, and they can request that a photocopy of the full text of any article be mailed to them.