Data from two pharmaceutical marketing research databases, the National Prescription Audit and the National Disease and Therapeutic Index, were used to study trends in outpatient use of cholesterol-lowering drugs in the United States from 1978 through 1988. Retail pharmacies dispensed an estimated 4.4 million prescriptions for cholesterol-lowering drugs in 1978. This declined to 2.6 million in 1983 and increased dramatically to nearly 13 million in 1988. This fivefold increase between 1983 and 1988 was accounted for primarily by the introduction and use of two new drugs, gemfibrozil and lovastatin, and, to a lesser extent, by the increasing use of some older drugs. In 1988, after 1 full year of marketing, lovastatin was the leading cholesterol-lowering drug, followed closely by gemfibrozil; both drugs are currently considered second-line agents. Clofibrate and dextrothyroxine, drugs that ranked first and second in 1978, declined to ranks of sixth and eighth out of eight in 1988. Cholestyramine, gemfibrozil, and lovastatin accounted for about 75% of all lipid-lowering prescriptions in 1988. From 1978 through 1988, an average 54% of individuals using cholesterol-lowering drugs were 60 years of age or older. The 13 million prescriptions for cholesterol-lowering drugs in 1988 represent a maximum estimate of 13 million treated individuals. This number compares with the 60 million Americans with high cholesterol levels who are candidates for dietary advice, and, if cholesterol levels do not improve, for combined diet and drug intervention.