The impact of black-white differences in the prevalence of risk factors for coronary heart disease on the outcome of coronary bypass surgery has not been well defined. Preoperative status, coronary anatomy, and surgical results were reviewed in 54 black males operated on between December 1970 and August 1983. With the use of criteria established by the New York Heart Association, five patients were classified in class II, 34 were in class III, and 15 were in class IV. Five patients had unstable angina. The most common risk factor, cigarette smoking, occurred in 43 patients (80%). Thirty patients (56%) had hypertension, 10 (19%) were diabetic, 14 (26%) were obese, and 23 (43%) had a family history of coronary disease. Elevated cholesterol and triglyceride levels were present in 8 and 12 patients, respectively. An average of 2.9 grafts per patient was placed. Overall operative mortality was 5.6%. Prior to the use of cardioplegia in 1978, there were two deaths among 14 patients (mortality, 14%). Since 1978 there has been one death among 40 patients (mortality, 2.5%). Although immediate operative mortality appears not to be affected by black-white status, long-term prognosis may be influence significantly by the high prevalence of hypertension and diabetes and the lower prevalence of hyperlipidemia among black patients.