With increasing frequency more elderly patients are referred for coronary artery bypass surgery. The operative results of 201 patients 70 years of age and over were compared with the results of 1242 patients under 70 years operated on since 1981. A larger percentage of the elderly patients had triple-vessel disease (66.2% vs 51.0%, p less than 0.001), left main coronary artery obstruction (34.8% vs 16.3%, p less than 0.01), and an ejection fraction of less than or equal to 45% (30.8% vs 21.1%, p less than 0.001). An increase percentage of the patients 70 years of age and over had perioperative myocardial infarction (7.9% vs 4.1%, p less than 0.05), required prolonged ventilatory support (7.9% vs 3.1%, NS), and had major neurologic complications (4.0% vs 1.1%, p less than 0.001). The mortality rate was significantly higher in the elderly patients (5.9% vs 1.9%, p less than 0.01) but did not correlate with degree of coronary artery disease, anginal pattern, or preoperative ventricular function. Only 2 of 12 deaths in the elderly patients were from cardiac causes. This data would suggest that elderly patients have an increased risk for significant cardiac and noncardiac morbidity and mortality following coronary artery bypass surgery and that the higher mortality rate in this age group may be a result of noncardiac organ failure.