The important role of physicians in the generation of medical care costs is evident, but methods of inducing physicians to participate in cost-containment efforts are not well developed. Efforts to change physicians' use of medical services have included education, peer review and feedback, administrative changes, participation, penalties, and rewards. Although educational programs have had mixed success, those using individualized instruction have been most effective. Several feedback and peer-review programs have demonstrated reductions in costs, as have administrative interventions. While penalties and direct rewards may be effective, alterations in the current reimbursement system could offer financial incentives to physicians who practice in a cost-effective manner.