Between September 1971 and June 1985, 230 Björk-Shiley valves were implanted for mitral valve disease at the Department of Surgery, University of Turku. Concomitant cardiac surgical procedures were performed in 35.2% of the cases. The follow-up period was between 1 month-13 years 4 months, with a total follow-up of 986 patient years. The early mortality was 4% in patients with isolated MVR and 10% where concomitant procedures had to be performed. Since the use of cold cardioplegia there has been no mortality for isolated MVR and the mortality rate for patients with concomitant procedures has been 3.9%. During the follow-up the rate of thromboembolism was 0.4 per 100 patient years, that of thrombolic encapsulation 0.4 and anticoagulant-related haemorrhage 0.7. Ninety-five per cent of the patients were free from thrombotic or embolic complications at 5 and 10 years after surgery. The survival rate was 79% at 5 years and 72% at 10 years. Considering these results we still prefer the Björk-Shiley valve in mitral valve replacement.