We have studied 159 patients 80 years of age or older who have had isolated coronary artery bypass grafting (CABG) since 1977. Eighty-seven percent have had surgery since 1984. Two thirds of the patients were male, and the mean age was 82 years. Most patients (97%) were in New York Heart Association (NYHA) functional class III or IV, 89% had unstable/postinfarction angina pectoris, and 67% had rest pain. Almost half (47%) required preoperative admission to the coronary care unit, 6% required preoperative use of an intra-aortic balloon pump, and 20% were operated on emergently. Significant left main coronary artery disease (greater than or equal to 50% stenosis) was present in 41%. Ten patients (6.3%) died within 30 days of surgery, with seven more patients dying during the same hospital admission or soon after transfer to another institution. This resulted in an overall hospital mortality of 10.7%. The median hospital stay was 10 days. On univariate analysis, the significant predictors of hospital mortality were NYHA IV, angina at rest, preoperative admission to the coronary care unit, emergency operation, ejection fraction less than 0.50, and the presence of mitral regurgitation. On multivariate analysis, ejection fraction less than 0.50 was the only significant risk factor (p less than 0.01). Of hospital survivors, 98% have been followed for a mean of 29 months. The estimated 5-year survival (+/- SEM) of all patients was 71 +/- 4.5%, and for hospital survivors, 80 +/- 4.5%. The most important predictor of adverse survival was an ejection fraction less than 0.50. Seventy-nine percent are angina-free, and 89% are in NYHA classes I and II. The majority of patients felt that they were improved by surgery. We conclude that CABG in patients 80 years or older, although associated with increased operative risk, gives excellent relief of symptoms and good 5-year survival. Patients should not be denied CABG because of age alone.