We investigated relation of operative mortality with factors such as during from onset to operation, cardiac tamponade, age (more than 70 years old), aortic regurgitation, and shock. Fourteen patients underwent emergent surgery for DeBakey type I acute aortic dissection. These patients were the basis for this reports. Operative mortality was 43% (6/14). Although not statistically significant, there was a trend toward preoperative cardiac tamponade, namely the patients with preoperative tamponade had a poor prognosis. Causes of death were as follows, two patients related to the residual false lumen, two patients to surgical procedure, one patients to ischemic heart and one to mis-swallowing after operation. Among two patients who related to the residual false lumen, one died of rupture of the descending aorta that the clamping was performed during operation and the other occlusion of superior mesenteric artery 43 days after operation. Causes of deaths in patients in relation with surgical procedure were brain death and postoperative bleeding in 1 each. We concluded that the residual false lumen is a risk factor in the peri-operative stage.