Ten-year survival percentages were calculated for groups of 407 initially medically treated patients and for 390 patients who had early coronary bypass surgery; all had either mild angina pectoris or myocardial infarction without subsequent angina pectoris. Uncensored actuarial survival was 77% for medical patients and 83% for the surgical group. For 179 patients who had internal thoracic (mammary) artery grafting as part of their procedures, survival was 91% in contrast to 76% for those who had vein grafts only. A sharp drop of the survival curve for the vein graft group after the seventh year was not shown for those who had internal thoracic artery grafts. Survival was 71% for 280 patients treated medically only.