The value of saphenous vein bypass surgery in the treatment of coronary artery disease will eventually be assessed through prospective randomized studies of homogeneous groups of patients undergoing either medical or surgical treatment. At present, there is insufficient evidence to demonstrate the beneficial effects of coronary bypass operations on prevention of myocardial infarction and prolongation of life. The improvement in the quality of life may be rewarding in patients with crippling angina pectoris in whom there is a major obstruction of the proximal coronary artery with good distal runoff and adequate ventricular function. This review summarizes our knowledge of the natural history of angina pectoris and examines the indications for a surgical approach in chronic, stable angina pectoris, in unstable angina, variant angina, main left coronary artery disease and acute myocardial infarction. Criteria for patient selection are tentatively defined.