Considerable evidence links elevated blood cholesterol levels to the development of atherosclerosis. The National Cholesterol Education Program (NCEP) has recently published revised guidelines for detecting and treating hypercholesterolemia in adults. Included in these guidelines is the recommendation that all adults older than 20 years of age know their cholesterol levels. Under the NCEP guidelines, knowledge of cholesterol levels, even if the levels are elevated, does not automatically lead to drug therapy; on the other hand, under these guidelines, adults are not automatically excluded from treatment simply on the basis of age or sex. The guidelines presented by the American College of Physicians in this issue differ from the NCEP guidelines in that they recommend only limited screening, primarily for middle-aged men. This recommendation is based in part on the assumption that overuse of cholesterol-lowering drugs will otherwise become a problem. In fact, a major current problem is underuse of cholesterol-lowering medications, even in patients at high risk for coronary events. The guidelines proposed by the College minimize large elements of the database linking cholesterol to atherogenesis and make unwarranted and unproven assumptions about physician behavior. In its rationale, its potential consequences, and the process by which it was derived, this policy is in error and should be rejected.