Seventy-one consecutive patients over 70 years of age underwent isolated coronary bypass surgery for left main coronary artery (LMCA) disease between September 1975 and December 1982. All patients had angina; 6% were in NYHA functional class II, 30% class III, and 64% class IV. Intravenous nitroglycerin was required in 25% of patients. Resting electrocardiogram was abnormal in 91% of patients and stress testing performed in 24 patients was positive in all. Degree of left main stenosis graded by diameter was 60 to 70% in 24% of patients and greater than 70% in 76%. In addition to left main stenosis 66% of patients had significant triple vessel disease. Left ventricular end diastolic pressure (LVEDP) was elevated in 69% of patients while ejection fraction (EF) was low only 24%, without correlation between high LVEDP and low EF. Mean number of bypass grafts per patient was 3.4 +/- 0.6. Hospital mortality was 7% and mean post-operative stay was 10.4 +/- 2.0 days. Stepwise multiple regression analysis of 12 variables identified only unstable angina requiring intravenous nitroglycerin as a significant predictor of hospital mortality (p less than 0.01). Follow-up was complete with a late cardiac mortality of 4.5%. Seventy-five percent of surviving patients assessed their quality of life as good at a mean follow-up of 26 months. Coronary bypass for LMCA disease in a non-selected elderly population can be performed with low operative mortality and marked improvement in quality of life.