In the surgery of acute aortic type A dissection we have employed preoperative and intraoperative Doppler sonography, to check safe and correct perfusion of the carotid arteries by the cardiopulmonary bypass before instituting cardiac arrest. Ten patients, operated upon for acute aortic type A dissection, were evaluated by means of Doppler sonography and in two patients a very abnormal flow pattern was found in the carotid arteries at the moment of aortic cross-clamping; immediate unclamping allowed temporary antegrade carotid perfusion, while the perfusion technique was readjusted. We report our experience with preoperative and intraoperative Doppler sonography, which appears to be a valuable new method of improving the surgical management of acute aortic type A dissection.