The purpase of the study was to aim at no-blood transfusion in the operation of descending thoracic aortic aneurysm. This policy was suported by means of the assist devices and techniques as follows ; 1. Heparin-coated left heart bypass or inter-arterlal shunt sets with pomp (5 cases) and without pump (5 cases). 2. Autotransfusion of the blood (Average 867 ml). 3. Geratin pre-cortet artificial prosthesis. 4. One-lung ventilation cannula. 5. Hypothermmic anesthesia (Average of the body temperature 33.3℃) and 6. Use of Erythropoietin after operation. Ten patients with true descending thoracic aortic aneurysms were electively operated. The average age was 61 years, and seven of them were male. The aorta was closs-clamped (mean 101 min.) and graft replacement was performed. The average blood loss during operation was 948ml. No blood transfusion was done in 3 cases. All the patients were discharged after uneventful courses This desease would be operated without blood transfusion in future