We studied a cohort of 2275 blacks and whites of both sexes in Charleston County, South Carolina, during the period of 1960-1961 to 1974-1975. There were 93 prevalent cases of coronary heart disease (CHD) at intake, and 317 new cases occurred by 1975 in persons originally free of CHD. White males had the highest incidence rates for all types of CHD and acute myocardial infarction (AMI). Black males and black females had the next highest rates. The incidence of angina pectoris in black females was double the rate in white females and five times the rate in white males. The rate of sudden death in black males was two and one-half times the rate in black females, three times the rate in white males, and four times the rate in white females. One hundred and one black males who had been selected on the basis of high socioeconomic status (SES) had AMI and CHD rates half that of other black males. None of the high SES black males experienced angina pectoris, AMI death, or sudden death during the observation period.