We developed a computer-based outpatient medical record system to facilitate direct physician interaction with the clinical computing system at the Beth Israel Hospital in Boston. During the 2 years since the medical record system was installed, 20 staff physicians, 5 fellows, 64 residents, and 11 nurse practitioners have entered 15,121 active problems and 1996 inactive problems for 3524 patients, as well as 12,651 active medications and 1894 discontinued medications for 3430 patients. Another 20,321 items were entered on health-promotion and disease-prevention screening sheets, and with the help of automatic updating by the computer, an additional 21,897 entries on screening sheets were made for 8686 patients. Clinicians wrote 10.9 +/- 12.8 (mean +/- SD) words per problem when they were working at the computer, as compared with 4.3 +/- 2.5 words per problem when they were writing in the paper medical record. We conclude that physicians will readily enter data directly into a computing system when they are given appropriate tools, and that they consider the computer-based problem list to be a valuable improvement over its paper counterpart. Use of a computer-based medical record system has obvious benefits for data management and patient care.