There is overwhelming evidence that increased cholesterol levels are associated with increased risk of cardiovascular disease. This study examined whether lowering of cholesterol through drug therapy in people who had coronary artery disease as determined by angiography led to regression of the disease, again as indicated by angiography and reduction in mortality or nonfatal myocardial infarction. The study should be contrasted with the Coronary Primary Prevention Trial (CPPT), which determined whether lowering cholesterol through a combination of drug and diet therapy resulted in decreased cardiovascular mortality. It should be noted that patients in the CPPT did not have known preexisting coronary heart disease.