Aortic dissection is an evolving process that may require one or several reoperations after the initial emergency repair. From January 1977 to September 1993, 148 patients underwent emergency surgery for type A acute aortic dissection. The replacement of the ascending aorta was extended to include the transverse arch in 43 patients (29%). One hundred fifteen patients (78%) survived surgery. During the same period, 37 patients required reoperation once (28), twice (7), or three times (2), for a total of 48 reoperations. Twenty-one patients had undergone initial repair in our institution; 16 patients had been operated on elsewhere. Reoperation was indicated for: aortic valve disease (4); a new dissecting process (7); threatening aneurysmal evolution of a persisting dissection (34); or false aneurysm (3). The re-do procedure involved: the aortic root and/or ascending aorta in 12 cases (group I); the ascending aorta and the transverse arch in 6 cases (group II); the transverse arch alone in 8 cases (group III); the transverse arch and descending aorta, or the descending aorta alone in 11 cases (group IV); and the thoracoabdominal aorta in 11 cases (group V). Risk factors for reoperation were analyzed in the 115 survivors initially operated on at our institution. Seven of 20 Marfan patients (35%) versus 12 of 95 non-Marfan patients (12.6%) required reoperation (p < 0.02). None of the 31 patients surviving arch replacement at initial repair required a reoperation, versus 21 of 84 (25%) patients surviving replacement limited to the ascending aorta (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)