Revascularization of the spinal arteries with thoracic aortic aneurysm were performed on nineteen patients using partial extracorporeal bypass. They were 16 men and 3 women. Age range were from 33 to 70 years (mean 49.9 +/- 10.3 years). There were eleven patients of dissecting aneurysm (DeBakey type IIIb in eight patients, type I in two patients and type IIIa in one patient), and eight patients of non-dissecting thoracoabdominal aneurysm (including two patients with ruptured aneurysm). The number of revascularized spinal arteries were 60 pairs (average 3.2 pairs per each patient). The revascularized spinal arteries were localized between levels T4 and L5.36 pairs of the 60 existed between levels T8 and L2 from where the artery of Adamkiewicz arises. Seven patients (eleven spinal arteries) underwent selective angiography of the revascularized spinal arteries postoperatively, and the anterior spinal artery and the artery of Adamkiewicz was identified in three patients. Two patients died within one month, one from MOF and the another from intestinal perforation respectively (operative mortality 11.1%). One patient, with ruptured thoracoabdominal aortic aneurysm showed paraparesis postoperatively, but no paraplegia was found in any patients. We recommend that not only the artery of Adamkiewicz but also the spinal arteries at the midthoracic area from T4 to T8 should be revascularized, to prevent postoperative paraplegia. Replacing of extended thoracic aneurysm, our method (using partial extracorporeal circulation and segmental aortic clamping) was thought to prevent spinal cord ischemia.