Background Three landmark trials involving 3-hydroxy-3-methylglutaryl–coenzyme A reductase inhibitors (statins) were published between 1994 and 1996 (the Scandinavian Simvastatin Survival Study [4S], the West of Scotland Coronary Prevention Study, and the Cholesterol and Recurrent Events trial). These trials provided evidence that lipid-lowering therapy decreases cardiovascular events, including mortality. Whether these recent data caused a shift toward statin use has not been evaluated. Methods Data from the National Ambulatory Medical Care Survey in 1980, 1981, 1985, and 1989 through 1998 were used. We analyzed 5053 visits by patients taking lipid-lowering medications to office-based physicians selected by stratified random sampling. The main outcome measure was use of specific lipid-lowering medications, including statins. Results In 1980 resins and niacin were the most commonly used lipid-lowering medications. By 1985 rising use of fibrates caused reductions in niacin use and resin use. By 1989 statins replaced fibrates as the most heavily used medications. Statin use climbed continuously thereafter, accounting for 90% of visits by patients treated for hypercholesterolemia in 1998. In time series analyses, increases in overall statin use were temporally unrelated to the publication of clinical trials, although the 4S trial may have contributed to a shift from older statins to simvastatin. For patients receiving lipid-lowering therapy in 1993 to 1998, statin use was significantly more likely for female patients, white patients, and patients visiting cardiologists. Conclusions Although the market for lipid-lowering medications is dominated by statins, the rise in statins predated the recent clinical trials supporting their use. (Am Heart J 2001;141:957-63.)