From October, 1986, to June, 1992 16 patients, 13 male and 3 female patients ranging in age 28 to 70 years, were operated on for thoracic aortic aneurysm, The etiology of these patients was atherosclerotic in 10, cystic medial necrosis in 4, and trauma in 2 cases, All patients were treated by use of CPB and circulatory arrest was applicated in one patient, Ten patients had aneurysms involving ascending aorta and six patients had descending aortic aneurysm, Among ten patients with ascending aortic aneurysm, annuloaortic ectasia with aortic regurgitation were seven and all underwent surgery with composite technique [Bentall operation], The other six patients with descending thoracic aneurysm were performed graft replacement. There was no early mortality but two late deaths occurred due to cerebral hemorrhage and renal problems at POD 3mo and 39mo respectively, We obtained satisfactory long-term results and overall survival rate at 5 year was 74.7%.