Clinical coronary heart disease (CHD) occurred in 257 subjects during eight to nine years of follow-up (average, 8 1/2 years) in a prospective study of 39- to 59-year-old employed men. Incidence of CHD was significantly associated with parental CHD history, reported diabetes, schooling, smoking habits, overt behavior pattern, blood pressure, and serum levels of cholesterol, triglyceride, and beta-lipoproteins. The type A behavior pattern was strongly related to the CHD incidence, and this association could not be explained by association of behavior pattern with any single predictive risk factor or with any combination of them.