ACBGS is indicated in patients with stable angina who have left main coronary artery disease; three-vessel disease; three or four of the clinical variables set forth in the Veterans Administration Cooperative Study; obstruction in proximal third of left anterior descending coronary artery as part of two- or three-vessel disease; and two- or three-vessel disease and exercise-induced ischemic ST-segment depression greater than or equal to 1.5 mm. ACBGS may increase survival in patients with limited exercise capacity. Finally, ACBGS may be indicated to increase the quality of life in patients with disabling angina that is refractory to medical treatment. Patients with unstable angina who have an inadequate response to intensive medical therapy should have emergency ACBGS. Indications for elective ACBGS in patients with unstable angina who respond adequately to medical therapy are the same as those for stable angina. Patients with rupture of the ventricular septum, acute severe mitral regurgitation, and cardiogenic shock with vessels suitable for ACBGS should have urgent ACBGS after acute myocardial infarction. Patients with postinfarction angina after the first few days following acute myocardial infarction, especially non-Q-wave infarction, should be considered for ACBGS. Indications for elective ACBGS in postinfarction patients are the same as those in stable angina. Patients with coronary artery disease, especially those with a significant amount of ischemic myocardium, who must undergo cardiac surgery for valvular heart disease or for congenital heart disease should probably have ACBGS performed at the time of surgery.