The high rate of necropsy in deaths among permanent residents of Rochester, Minnesota, provided a unique opportunity to study the prevalence of coronary heart disease and the frequency and mode of death resulting from this disease. In this community of approximately 30,000 population, necropsy was done in 73 per cent of all resident deaths during the years 1947 through 1952. Included in this group were 691 necropsies that represented 67 per cent of the 1,026 deaths of persons 20 years of age or older.Coronary heart disease caused death in 221 patients (23 per cent of all necropsies and 32 per cent of all necropsies on adults). These 221 coronary deaths in adults represented 41 per cent of the men and 22 per cent of the women. The coronary deaths were attributed to acute coronary failure (sudden death) in 94 patients (43 per cent), acute myocardial infarction in 87 patients (39 per cent), congestive heart failure in 32 patients (14 per cent) and thromboembolism in eight patients (4 per cent). The 87 patients dying during acute myocardial infarction died of congestive heart failure (30 per cent), myocardial rupture (24 per cent), acute coronary failure (23 per cent), and thromboembolism (14 per cent), with the remaining 9 per cent dyingof a combination of acute myocardial infarction and additional serious systemic disease.The greatest number of deaths from coronary heart disease occurred during the seventh decade of life in men and the eighth decade in women. At least one coronary artery exhibited from 25 to 100 per cent obstruction from atherosclerosis in 513 hearts (74 per cent of the adult necropsies).These necropsies, representing two thirds of all deaths in adults in this community, disclosed that significant coronary-artery disease was present in three of four adults and was the cause of death in four of 10 men and two of 10 women.