The guidelines developed by the Adult Treatment Panel of the National Cholesterol Education Program identified low density lipoprotein (LDL) as the major atherogenic lipoprotein, and high levels of LDL-cholesterol as the primary target for cholesterol-lowering therapy. Low levels of high density lipoprotein (HDL)-cholesterol were recognized as a major risk factor for coronary heart disease. This report reexamines in depth the recommendations of the Adult Treatment Panel on HDL-cholesterol. Two major questions are discussed: (1) Should HDL-cholesterol levels be measured in all adults, as recommended for total cholesterol? (2) Should patients found to have a low serum HDL [corrected]-cholesterol level (less than 35 mg/dL [less than 0.91 mmol/L]) enter medical therapy to raise the level? The guidelines of the Adult Treatment Panel are reaffirmed as appropriate from the current perspective. These guidelines recommend that HDL-cholesterol levels be determined in patients deemed to be at high risk for coronary heart disease and suggest that HDL measurement is optional for individuals with borderline-high total levels. The guidelines of the Adult Treatment Panel recommend that low HDL-cholesterol levels be raised mainly by hygienic means (ie, smoking cessation, weight loss, aerobic exercise). When drug therapy is required for high LDL-cholesterol levels in the presence of low HDL levels, cholesterol-lowering drugs that concomitantly raise HDL should be given first priority.