From April, 1984 to April, 1989, 104 heart valve replacements were performed in 103 patients. The atrio-ventricular valves (97 mitral and 7 tricuspid valves) were replace by bioprosthetic valves mounted on the flexible stent made of Elgiloy. They included 91 porcine aortic valves and 13 bovine pericardial valves. Only 74 patients recovered and discharged from the hospital because of high operative mortality of re-replacement and double valve replacement (19 and 30 patients, respectively). These patients were followed-up for 8 to 68 months with a total follow-up period of 297 patient-years. Two patients developed cerebral embolism and two developed bacterial endocarditis. The incidence of the two complications was 0.67%/patient-year. No valve failure occurred. Long-term results of bioprosthetic heart valves mounted on flexible stent were better than those mounted on rigid stent.