A group of 390 patients with mild angina pectoris or myocardial infarction without subsequent angina had early coronary bypass operation. Five year survival was significantly higher (95.4%) than in a similarly selected medically treated group (88.5%) reported before. One death occurred in the 30 day postoperative period. Five year survival in the 179 patients who had internal mammary artery grafts was 98.9%. Survival for patients with mild angina and satisfactory left ventricular function (96.2%) was significantly higher than in the medical subset (91.3%). In the patient population studied, five year survival was higher in patients who had early bypass operations than in those who did not.