Between 1973 and 1985, 81 patients underwent Bentall's operation. 90 p. 100 of the patients had cystic medionecrosis, but only 24 showed signs of Marfan's syndrome. It must be noted that 12 patients were reoperation cases, 18 were operated upon in an emergency for tamponade (stage V) on acute dissection, and 7 had lesions that involved the aortic arch. The operative procedure was that described by Bentall; Cabrol's modification was used in only 26 patients. The most recent improvements concerned myocardial and (in case of aortic involvement) cerebral protection with an autonomous perfusion of blood at very low temperature. Mortality was low in patients with annulo-aortic ectasia (1 death in 53 cases; 1.8 p. 100) and rose to 34.5 p. 100 (33.3 p. 100 in reoperation cases) in patients with chronic dissection. Evaluation of mortality by stage showed virtually no risk in stages I and II, whereas 4 of the 9 stage IV patients died within the first post-operative month. Late mortality with a mean follow-up of 4 years was 14.2 p. 100; 2 of the 10 deaths were accidental, and 4 of the remaining 8 deaths were due to the anticoagulant therapy (death was precipitated in 2 cases by the presence of a cerebral aneurysm). No case of systemic embolism was observed, and the authors raise the question of whether long-term anticoagulant therapy should be abandoned. None of the patients who underwent Bentall's operation were reoperated upon, whereas 7 out of the 23 patients who had had supracoronary aortic replacement before 1976 had been reoperated upon within a few years.(ABSTRACT TRUNCATED AT 250 WORDS)