Second surgical opinion programs (SSOPs) have been used since 1972 by both public and private insurers to improve the patient's information and decision processes and to reduce operative risks and costs attributable to questionable and perhaps unnecessary operations. This article reviews the literature on SSOPs. It considers whether SSOPs are effective mechanisms for reducing health care costs, how SSOPs affect outcomes, how physician errors affect the value of SSOPs, and what noncon-firmation rates and rates of surgery indicate about the appropriateness of operations. Although the literature varies in quality, all the studies fall short in one or more of the following dimensions: an appropriate control group, a comprehensive definition of cost and outcomes, and sufficient duration and scale to measure changes and use of medical services in a general population. Thus, the value of SSOPs remains an open question.