A total of 790 patients underwent isolated (N = 520) or mitral valve replacement associated with a tricuspid valve procedure for lesions excluding post-myocardial infarction mitral regurgitation. The mean age was 54 years: the sex ratio was 1.9 +/- 1.1, female/male. Three hundred and four patients (38.5%) were in the NYHA functional class II and 406 patients (61.5%) were in classes III or IV. The operative mortality was 9.7% (77 patients). The factors associated with a high operative risk were, on multifactorial analysis: double valve replacement, age over 70 years, NYHA class IV, aortic clamp time over 68 minutes and the presence of mitral regurgitation. Seven hundred and four of the 713 survivors were contacted (98.7% follow-up). The average follow-up period was 5.05 years (range 11 to 219 months) giving a total of 3,997 patient-years. The 5 and 10 year actuarial survival rates were 74.7% and 64.7% respectively. The presence of a tricuspid lesion requiring surgical correction, a high NYHA classification and the presence of mitral regurgitation were poor prognostic factors of long-term survival. Three hundred and sixteen of the 533 survivors at the time of the inquiry were in NYHA class I (59.3%), 188 in NYHA class II (35.3%) and 29 in NYHA class III or IV (5.4%). Mitral valve replacement should be considered early as the immediate and long-term results are closely related to the preoperative myocardial function.