Peer review affords a privilege for medicine to participate in the shaping of its future. As a corollary, however, medicine must accept the responsibility of stewardship which attends this privilege. Physicians must be willing to participate even more actively in peer review.Properly, utilization review of professional medical services can be performed only by physicians. They may be assisted by informed lay personnel and by computer-derived data. In no instances, however, should judgment of medical necessity be rendered by computer alone. Although an important function of peer review is the control of health care costs, even more important is the evaluation of the quality of care provided the consumers-our patients."Due process" must be an integral feature of peer review. Any provider must be given the opportunity to discuss his pattern of practice with his peers, and an appellate mechanism must be available.Prospective, rather than retrospective review is preferable, although both approaches are necessary.