The hospital mortality and major factors contributing to hospital morbidity and postoperative length of stay were examined in 597 consecutive patients 70 years of age and older who underwent isolated coronary artery bypass grafting (CABG) between January, 1978, and December, 1983. The mean age of the patients was 73 years, and 66% were men. Unstable angina was present in 59% of patients, left main coronary disease in 13%, and moderate or severe left ventricular dysfunction in 10%. The mean number of arteries grafted per patient was 3.4. The hospital mortality was 2.7% (16 patients) and was higher than the mortality among 4,125 patients less than 70 years of age (0.4% in 18 patients) operated on during the same interval (p less than 0.001). In multivariate regression analyses, age of 80 years or greater, evolving myocardial infarction, serious coexisting illness, major left ventricular dysfunction, emergent operation, and the development of major postoperative complications were significant (p less than 0.05) independent predictors of increased hospital mortality. Major complications occurred in 135 patients (23%). In multivariate analyses, the presence of vascular disease, serious concomitant illness, and the need for urgent or emergent operation were significant independent predictors of the development of major postoperative complications. The mean duration of postoperative hospital stay was 10.6 +/- 6 (standard deviation) days. In multivariate analyses, the development of major postoperative complications was the only variable independently predictive of prolonged hospital stay. With current techniques, CABG procedures can be safely performed in the elderly with mortality and morbidity rates only slightly higher than those in younger patients.(ABSTRACT TRUNCATED AT 250 WORDS)