Emergency surgery of acute dissection of the ascending aorta is generally a palliative procedure aimed at preventing the vessel from rupturing into the pericardium. Evolving dissecting aneurysm or recurrence of the dissection process is, therefore, a common complication and may lead to reoperation or death. Between January 1970 and December 1988, 133 patients were operated upon for acute dissection of the ascending aorta. During the same period, 22 patients underwent 26 reoperations for recurrent or evolving dissection. Eleven (50%) patients had Marfan's syndrome. Thirteen patients had been operated upon previously in our institution and 8 had been operated upon elsewhere. In 10 patients, the intimal tear had not been resected during the first operation. Operative procedures varied according to the pathoanatomical features and consisted generally of an extended resection of the aortic arch. Eight reoperations were performed as emergencies and 18 were performed electively. Hospital mortality rate was 18% (4/22). Late follow-up ranged from 3 to 153 months (mean: 55 months) for a cumulative follow-up of 998 months. Late mortality was 27% (5/18) for a linearized rate of 6% pt/yr. The actuarial risk of reoperations is 13.7% +/- 7% and 21% +/- 11% at 5 and 10 years, respectively. Marfan's syndrome and persistence of the primary intimal tear are considered the main risk factors of reoperation, while emergency and thoraco-abdominal replacement are the main risk factors at reoperation.