Volunteers were selected for the trial through a series of three screening visits, which began in November 1973 and were completed by February 28, 1976. From among 361,662 men seen at first screening, 12,866 were found to be eligible and were randomized into the trial. Half of the participants were assigned to the special intervention group and half to the usual care group. The special intervention group was advised to follow an eating pattern designed to result in a nutrient intake of 30 percent to 35 percent of calories from fat, with 10 (later 8) percent from saturated and 10 percent from polyunsaturated fat; approximately 300 (later 250) mg of cholesterol; and modification of carbohydrates as needed for individual requirements. This group was also encouraged to cease cigarette smoking by a combination of techniques, including counseling and audio-visual aids. Hypertension management was based on a stepped-care program of weight reduction and drugs similar to that used in the Hypertension Detection and Follow-up Program. Those in the usual care group were referred to their personal physician or other source of care for such management of their risk factors as considered appropriate by these providers. The primary endpoint was death due to coronary heart disease. Men in both the special intervention and usual care groups returned for assessment of changes in risk factor levels annually. A medical history was taken and a physical examination performed. An electrocardiogram was also obtained for centralized reading to identify non-fatal myocardial infarction as an additional endpoint.