From January 1980 to December 1988, 44 patients with chronic aortic dissection and aortic insufficiency underwent operation. This group of patients was analyzed to evaluate the outcome of those in whom the aortic valve was preserved compared with those having valve replacement. The overall preoperative characteristics of the two groups were similar except for the incidence of Marfan's syndrome. Valve replacement was the elected procedure in patients with valve degeneration or annuloaortic ectasia. In patients with leaflet prolapse with or without an enlarged annulus, a plastic procedure was used. In 48% of the patients, it was possible to preserve the valve. There were five hospital deaths (11%): three were due to low-output syndrome, one was due to bleeding, and one was due to neurological complications. There were two late deaths (5%). Follow-up of the 37 surviving patients ranged from 2 to 108 months (mean follow-up, 18 months). Seventy-eight percent of the survivors were in functional class I and the others were in class II. Two patients in whom the aortic valve was preserved had mild aortic insufficiency. Three patients with bioprostheses underwent reoperation because of prosthetic valve dysfunction. One patient who had aortoplasty and an aortic valve plastic procedure was seen with redissection and aortic insufficiency after 60 months and was reoperated on using the Bentall technique. The actuarial survival curves showed that patients who underwent valvoplasty had higher, but not significantly higher, survival rates than the valve replacement patients.(ABSTRACT TRUNCATED AT 250 WORDS)