Three hundred and thirty six Kay-Shiley disc valves were implanted in 323 cases from 1968 to 1975 at the Hacettepe University Hospital, Ankara. Eight patients died during surgery. Of the 328 valve replacements followed postoperatively, 263 were in the mitral (80.2%), 26 in the aortic (8%) and 39 in the tricuspid position (11.9%). Three hundred and fifteen patients were evaluated in the early and late postoperative periods. In the early period 52 patients died (16.5%). The remaining cases were followed up for 1-16 years (3381 patient-years). Twenty eight patients remain alive at the time of this report (10.6%). The longest survivors are 2 of the mitral valve replacement cases. The actuarial survival estimates were 88 +/- 2.4% at 1 year, 60.3 +/- 3.4% at 5 years, 36.3 +/- 3.9% at 10 years for all cases. The incidence of thromboemboli was 4.2% per patient-year in the late period in both the overall and the isolated MVR groups. Valve failure due to thromboses was detected in 8 patients (3%). Six patients were reoperated on in the late period (2.3%).