A review of 198 ruptured aortic aneurysms has been undertaken, this being 36.3 per cent of all the aneurysms treated during the period 1960-81. The overall mortality rate was 42.9 per cent. The peroperative mortality was 6.6 per cent and the mortality of the patients who survived the operation was 38.9 per cent. Factors which influenced postoperative mortality were the age of the patient, the distance travelled to hospital, the presence of an intraperitoneal bleed, the duration of the operative procedure and the volume of blood transfused, but only the amount of blood transfused had a statistically significant influence on mortality. However, as the highest mortality associated with any of these risk factors was 54.9 per cent, no single factor alone can be considered a contra-indication to operation. As there are no reliable predictive factors, we believe that all cases with clinically ruptured aortic aneurysms should have a laparotomy and resection. The most common postoperative complications were varying degrees of renal and respiratory insufficiency and the occurrence of these was significantly associated with the volume of blood transfused.