Survival rate and incidence of myocardial infarction after aortocoronary bypass operation in 274 patients are presented. Mortality was 5.1% within the first postoperative month and the 5-year-survival rate was 86%. There were 24 perioperative myocardial infarctions and another 21 infarctions over the next 5 years. Comparison of these data with the natural history of coronary heart disease suggests a possible prolongation of survival after bypass surgery. The incidence of myocardial infarction appears to be unchanged.