We studied whether furnishing care providers with computer-generated summaries of patients' current and past medications would reduce the time they spent on various drug-related tasks during patient visits. An observer used time-sampling methods to measure the amount of provider time spent on each of 10 activities during 166 clinic visits, some with profiles and some without them. Additional data were taken from the medical record on factors that might affect the time spent on various tasks. The results suggest that record reading time was reduced for first encounters between patients and providers in the medical clinics, where prescribing volume was highest; in other situations, no effect of profiles on record reading time was evident. Providers continued to document drug data in their progress notes, whether or not a profile was available, saving no time. Prescription writing required about one third less time when a profile was used than when a traditional prescription blank was used. Both uses of profiles for prescribing and the time saved per prescription also increased sharply with the number of drugs prescribed per visit.