This study was undertaken to assess the comparative preference of pharmacy outpatients for verbal and written medication information and to identify factors that might influence these preferences. Two hundred forty-seven consecutive, literate outpatients presenting with a prescription for a penicillin were enrolled in the study and given standardized verbal counseling by a pharmacist and a medication information leaflet. Assessment was made at initial presentation and by a prepaid mail questionnaire completed anonymously by the patient at home. Preferences were analyzed by age, sex, and number of medications prescribed. A response rate of 63 percent (155/247) was obtained. Low recall of physician instruction (11 percent) was recorded. Respondent preferences were for pharmacist counseling (30.4 percent), leaflet (20.6 percent), both of these (44.5 percent), or neither/uncertain (4.5 percent). The only factor having a statistically significant effect on these preferences was age (31-55 y), which influenced preference for a leaflet. Patient opinion of each leaflet section is presented. Patient preference for a leaflet or verbal counseling with a leaflet provides further evidence that leaflets should be widely used.