Mortality risk in coronary artery disease (CAD) is more closely related to angiographic findings of multiple coronary artery obstructions and left ventricular asynergy than to the severity of angina pectoris, the major symptom of CAD. Since coronary revascularization surgery is most frequently performed to relieve chest pain, there are few reports evaluating the results of coronary artery bypass surgery in patients with minimal or no angina pectoris but with anatomically severe disease. From July, 1970, through December, 1976, 844 patients had coronary artery bypass surgery performed at the Peter Bent Brigham Hospital for chronic or unstable angina pectoris. Twenty patients (2.3%) were operated on because of severe coronary obstruction but who had minimal or no angina. Fourteen patients underwent coronary arteriography because of a positive exercise tolerance test, and six because of a prior myocardial infarction. All but one patient had multivessel CAD, and four patients had significant left main coronary lesions. There was no operative mortality. One late death occurred 5 years postoperatively, for a 5.0% cumulative mortality. Average follow-up has been 34 months (range, 19 to 80 months). Of 12 patients with both pre- and postoperative exercise tests, eight have reverted to normal, and four show a less ischemic response to exercise. Coronary revascularization may have a beneficial effect on the patient with "asymptomatic" but anatomically severe CAD.