We evaluated the Björk-Shiley tilting-disc (BS) valve replacement up to the longest duration for about 12 years. The study was started in November 1982 and ended in September 1991. There were total number of 206 with 117 males and 89 females aged between 18 and 71 with a mean of 51.6. Eighty three patients had isolated aortic valve replacement (AVR), 92 had isolated mitral valve replacement (MVR), and 31 had AVR plus MVR. One hundred and fourteen spherical-disc valves were replaced in the aortic, 112 spherical and 11 monostrut in the mitral position. The mean duration of follow up was 6.5 years for a total of 1330.6 patient years (PY). Forty-one patients (3.8%/PY) died later, and 14 out of 41 died of valve-related complications. Actuarial survival rates for all, AVR, MVR and DVR at 10 years after operation were 71.2%, 73.5%, 73.9% and 55.4%, respectively. The linearized rates of thromboembolism (TE), thrombosed valve (TV), anticoagulant-related hemorrhage (ACH), prosthetic valve endocarditis (PVE), hemolysis (H), and reoperation (RO) were 1.2%/PY, 0.2%/PY, 0.7%/PY, 0.2%/PY, 0.1%/PY, and 0.2%/PY, respectively. The rates of freedom from TE, TV, ACH, PVE, H, and RO and 10 years after operation were 83.5%, 98.5%, 94.0%, 98.4%, 99.0% and 95.6%, respectively. The major causes of postoperative mortality and morbidity were TE, TV, and ACH. One hundred and fifty-six out of 161 patients showed an improvement in NYHA functional class post operatively. The surgical results of valve replacement with the BS valve was excellent and acceptable one. Intensive management with a special reference of anticoagulant therapy is necessary for a long-term management of the patients with mechanical valve replacement.