A model for improving physician prescribing that utilizes computerized feedback was studied in a family medicine residency practice. Resident and faculty physicians were stratified by level of experience and randomized into two groups. For 9 months the experimental group received monthly printouts identifying drugs they had prescribed by brand name with estimates of cost savings that might have been realized by prescribing generic drugs. The control group received no feedback. Prescription monitoring of both groups continued for 12 months after all feedback had ceased. Median weighted rates of generic prescribing for the experimental physicians were 14% for the baseline, 67% for the feedback, and 54% for the follow-up periods. Rates for the control physicians for the three periods were 32%, 37% and 31%, respectively. The increase in generic prescribing by physicians in the experimental group was significantly greater than for control physicians (P= 0.01). The feedback model improved rates of generic prescribing but should be evaluated for broader areas of physician prescribing.