Forty-five patients had acute aortic dissecting aneurysms. Ten patients were treated symptomatically with 10% survival rate and 13 patients were treated medically with trimethaphan camsylat, reserpine, and guanethidine sulfate with four survivors (30%). Twenty-two patients were treated surgically. Two died pre-operatively, 1 during aortography and the other during induction of anesthesia, five during surgery, and six postoperatively. The high operative survival rate (70%) was decreased by significant postoperative mortality. The one-year survival rate was 40%. Although specific indications for the medical treatment of acute aortic dissection exist, surgical therapy remains the treatment of choice.