Fifteen cases of ruptured thoracoabdominal aneurysm (-TAA) were encountered in 1987-July 1994. These patients included 13 males (86.6%), 2 females (13.4%) with a mean age of 66.3 years (range 58-78). Surgery was performed on 13 patients of whom 6 (46.1%) died within 30 days. The two other patients had died of heart failure prior to surgery. In 8 of these patients (53.4%) the condition was not diagnosed until clear symptoms had appeared. The ruptured aneurysms were thoracic in 9 cases (60%), abdominal in 6 (40%). The maximum aneurysm diameter in the most frequently ruptured group was 6.1-8 cm (in 9 patients-60%)./ For 5 cases (33.4%) the maximum diameter of ruptured aneurysms included dorsolumbar pain. In one patient a concomitant aortobronchial fistula had produced rupture. Low blood pressure was found in 9 cases (60%). In 5 cases (38.4%) curative surgery was performed within 24 hours of the onset of symptoms. In this group, the mortality rate was 40% (2 patients). In the remaining 8 cases, on whom surgery could not be performed within 24 hours (range 25 hours-4 months) the mortality rate was 50% (4 cases). All four cases of paraplegia (30.7%) were encountered among patients in the second group, 2 of whom died. Follow-up revealed a 5-year mortality rate of 71.4%.