Of 1,393 consecutive patients operated on for aneurysm of the abdominal aorta between 1964 and 1978, 61 consecutive patients had undergone emergency operation for ruptured abdominal aortic aneurysm, for an incidence of 4.4% (61 of 1,393). There were 57 men and four women; their mean age was 77.5 years, with a range of 49 to 93 years. In 21 patients the diagnosis of aneurysm had been known from 1 day to 5 years prior to rupture. Hypotension (less than 100 mm Hg systolic) was present in 27.9% of patients (17 of 61) on admission to hospital and prior to operation in a total of 44.3% patients (27 of 61). Operation was begun in eight patients with an initially unrecordable blood pressure. The perioperative mortality rate (30 day) was 14.8% (nine of 61). The two factors most influencing survival were age [no patient younger than 60 years died vs. 40% of patients (four of 10) older than 80 years] and the magnitude of blood loss (survivors lost a total of 4,513 ml vs. 8,500 ml in those who died). Thus the most common cause of death was myocardial infarction (six of eight) in elderly patients, secondary to poorly tolerated severe hypovolemia. The results of this study suggest the need for avoidance of technical problems during operations, earlier referral of patients with known abdominal aortic aneurysms, especially the elderly, and early diagnosis with immediate operation for ruptured aneurysms.