21 cases of Stanford type A aortic dissection (15 acute and 6 chronic) were treated with or without surgery in the last 38 months. Out of seven cases who were admitted before October, 1986, three cases were treated medically and all died suddenly within 30 days. The remaining four cases were operated upon as emergency with only one survival. Extensive hemorrhage was the cause of operative deaths. After November 1986, substantial reduction in hospital mortality (one death in eight acute cases) was accomplished by the following strategy for acute aortic dissection, i.e., (1) urgent operative intervention for cases with cardiac involvement, and initial medical treatment followed by elective operation at chronic stage for those without cardiac involvement, (2) routine use of open distal anastomosis, (3) preferential adoption of simple surgical intervention limited to the ascending aorta. There was no operative death in six chronic cases in spite of more extensive approach. These results suggest that the strategy mentioned above is reasonable in treatment for Stanford type A dissecting aneurysm.