A computer-assisted practitioner-response system was used to review cimetidine use in one hospital. All patients receiving cimetidine from April 1, 1981, through May 15, 1981, were identified daily using a computerized medication-profile system. A practitioner-response form, which asked the physician to indicate the reason for prescribing cimetidine, was placed in the chart of all patients receiving the drug. When these forms were collected, the reviewer scanned the chart for patient demographic information, duration of cimetidine therapy, and other drugs prescribed that potentially could interact with cimetidine. If the physician did not complete the form, the reviewer checked the chart for prescribing information. Cimetidine was prescribed for 10% (247) of all patients admitted during the study period. Seventy percent of the practitioner-response forms were completed; the indication for cimetidine use was obtained for an additional 20% through chart review. Seventy-five percent of the patients were exposed to a potential drug interaction. The most common reason for prescribing cimetidine was to prevent stress ulcers; only 15% of cimetidine orders were for FDA-approved uses. The computer-assisted practitioner-response system was an efficient method for reviewing cimetidine use. The computerized medication profile facilitated identification of patients receiving the drug, and the practitioner-response form provided the indication-for-use data more quickly than conventional chart review.