One hundred consecutive patients 80 years of age or older consented to and subsequently underwent open-heart operations at our institution between July 1976 and May 1987. Fifty of the patients had aortic valvular disease (28 with coexisting coronary artery disease), and 41 had isolated coronary artery disease. Eight patients had mitral valvular disease, and one had a dissecting aortic aneurysm. Ninety had Class IV disease that was functional, ischemic, or both. The most compelling indications for operation in 85 patients were unstable or postinfarction angina, syncope, acute pulmonary edema, or cardiogenic shock. Twenty-nine patients died soon after operation (within 90 days). New York Heart Association Class IV disease, previous myocardial infarction, cachexia, and emergency operation were preoperative variables associated with early death. Forty-three patients had no complications except for atrial arrhythmias and were discharged from the hospital a mean (+/- SD) of 11.5 +/- 3.7 days after operation. Low cardiac output, acute myocardial infarction, reoperation for bleeding, renal insufficiency, pneumonia, and prolonged endotracheal intubation were the most common serious postoperative complications. Twenty-eight patients who survived postoperative complications were discharged 24.9 +/- 19.6 days after operation. Seventeen patients died 2 to 104 months after discharge from the hospital. Actuarial calculation predicts the survival of 59 percent of patients at three years and 54 percent at five years. Of the 54 patients still alive at this writing, 53 have disease within New York Heart Association and Canadian Cardiovascular Society Classes I or II. For selected octogenarians with unmanageable cardiac symptoms, operation may be an effective therapeutic option.