Fifty-seven patients underwent repair of atherosclerotic thoracoabdominal aortic aneurysms between 1978 and 1990. Five patients had urgent surgery for rupture. The 30-day operative mortality rate for the entire group was 18% (10 patients). Before July 1987, 19 patients (group 1) were operated on by use of a technique previously described. In these earlier patients the peritoneum was routinely entered, the diaphragm was divided radially, and no heparin was given. Among patients in group 1 there was a 30-day operative mortality rate of 42% (8 patients), and morbidity included myocardial infarction 4 (21%), respiratory failure 9 (47%), renal failure 12 (63%), bleeding requiring reoperation 4 (21%), and intestinal ischemia 3 (16%). Since July 1987 a standardized approach to all elective thoracoabdominal aortic aneurysms has been used in 38 patients (group 2). This method uses a left thoracoabdominal incision, circumferential division of the hemidiaphragm, retronephric totally extraperitoneal aortic exposure, single lung anesthesia, full heparinization, the graft inclusion technique, and liberal use of visceral endarterectomy. Patients in group 2 sustained a 30-day operative mortality rate of 5% (2 patients) and morbidity included myocardial infarction 2 (5%), respiratory failure 10 (26%), renal failure 11 (29%), bleeding requiring reoperation 1 (3%), paraplegia 6 (16%), and paraparesis 4 (11%). Modern surgery for repair of thoracoabdominal aortic aneurysm results in acceptably low operative mortality rates. Spinal cord ischemia remains an unresolved source of morbidity.