Abstract An autopsy study of 83 consecutive nonresected ruptured arteriosclerotic abdominal aortic aneurysms and 199 nonruptured aortic aneurysms noted at postmortem examination from 1952 to 1968 at the Massachusetts General Hospital were reviewed with regard to aneurysm size. Over 18 per cent of nonresected aneurysms under 5 cm or less had caused death by rupture. The incidence of rupture of aneurysms measuring between 5.1 and 7 cm, 7.1 and 10 cm, and over 10.1 cm in diameter was approximately 20, 60, and 95 per cent, respectively. Of patients dying with ruptured aneurysms without resection, 80 per cent survived six hours, 50 per cent for twenty-four hours, 30 per cent for six days, and 10 per cent for six weeks. There was no common anatomic site of perforation and a great majority of these aneurysms might have been easily resectable from a technical viewpoint. The clinical report consists of sixty consecutive patients with ruptured arteriosclerotic abdominal aortic aneurysms operated on by this author during the past eight years. More than half the patients were in the eighth decade of life or more. Massive blood loss and shock were present preoperatively in three quarters of the group. About 20 per cent of ruptured aneurysms were 7 cm or under in diameter. Of sixty patients, eight died of shock on the operating table, five died from one to five days, and eleven from six to sixty days postoperatively. Thirty-six or 60 per cent of patients, however, survived to leave the hospital. On the basis of this experience, I would like to emphasize the importance of some newer technical considerations. These include preoperative emergency application of an antigravity suit, intraluminal control of massive aortic hemorrhage at operation, and a method of aneurysm resection which minimizes venous injury. Particular emphasis is placed on the importance of postoperative respiratory support determined by routine arterial blood gas monitoring. A number of early deaths may be preventable, particularly those relating to pancreatitis and bowel ischemia. In my experience, since the combined operative mortality and late graft failure rate with elective aneurysmectomy is under 4 per cent, all abdominal aortic aneurysms, with rare exceptions, should be surgically treated before rupture occurs.