This report of an expert panel of the National Cholesterol Education Program provides new guidelines for the treatment of high blood cholesterol in adults 20 years of age and over. Total cholesterol levels are classified as follows: less than 200 mg/dL--"desirable blood cholesterol"; 200 to 239 mg/dL--borderline-high blood cholesterol; greater than or equal to 240 mg/dL--high blood cholesterol. The guidelines detail which patients should go on to have lipoprotein analysis, and which should receive cholesterol-lowering treatment on the basis of their low density lipoprotein (LDL)-cholesterol levels and status with respect to other coronary heart disease risk factors. Dietary therapy is the primary cholesterol-lowering treatment. The report specifies the LDL-cholesterol levels at which dietary therapy should be started and the goals of therapy, and provides detailed guidance on the nature of the recommended dietary changes. If, after six months of intensive dietary therapy, LDL-cholesterol exceeds specified levels, drug treatment should be considered.