Seven percent of all health expenditures in the United States in 1987 was allocated for medications. Accurate prescribing decisions thus have crucial implications for both economic and clinical aspects of health care. A review of 44 empirical studies indicates that different strategies to improve the prescription practices of primary care physicians have proved effective to varying degrees; administrative reminders and feedback systems appear to be suitable for group practices, while one-on-one educational interventions may work well in less-structured office settings. Better-controlled trials and quasi-experimental designs, together with cost-benefit analyses, are still needed to enhance the efficacy and efficiency of prescribing practices.