One hundred consecutive patients who underwent resection of aneurysms of the left ventricle were reviewed. Eighty-four of these patients had resection or plication of an aneurysm of the anterior left ventricular wall either alone or in combination with coronary artery bypass grafting. In 27 patients who had little or no congestive heart failure, the primary indication for operation was disabling angina pectoris. In them the early mortality was 4% and late mortality, 4%. In nine other patients the primary indication for operation was life-threatening ventricular arrhythmias. In this group the early mortality was 56% and late mortality, 0%. Severe congestive heart failure was the primary indication for aneurysmectomy in 48 patients. In these patients the early mortality was 21% and late mortality, 34%. When the primary indication for operation was severe congestive heart failure, overall survival and postoperative results were best in patients in whom the nonaneurysmal left ventricle had good function preoperatively and was supplied by coronary arteries either unobstructed or favorable for bypass grafting; results were poorest in those patients with three-vessel coronary artery disease who had impaired motion of the lateral left ventricular wall and distal lateral wall vessels that were unfavorable for bypass grafting. It is concluded that patients with left ventricular aneurysms form a heterogeneous group in which the prognosis varies markedly. The probability of a good postoperative result can be predicted by careful preoperative analysis of a patient's symptoms, ventricular function, and coronary artery anatomy.