To evaluate the extension of the indications for operation and up-to-date problems in the surgical therapy of the acquired valvular disease, 581 consecutive patients of prosthetic valve replacement from January 1974 through December 1987 were analysed. The age at operation was 39.1 years (range 22 to 68) at 1974, but increased to 51.9 years (range 9 to 75) at 1987 (p<0.05). Early mortality was 3 deaths in 9 patients (33.3%) who were older than 70 years old, but its range was 0% through 7.7% in the younger patient group (p<0.05). Hospital mortality of the combined valve procedure for aortic, miral and tricuspid valvular disease was analysed. It was higher in the group of tricuspid valve replacement (30.0%) than the group of tricuspid annuloplasty (8.3%) (p<0.01). The former group was in poor preoperative state (cachexia, total bilirubin>2mg/dl, mean right atrial pressure>10mmHg and systolic pulmonary artery pressure >75mmHg), compared to the latter group. The cases of re-replacement of the prosthetic valve increased since 1985. The incidence of poor prognosis after operation, that included early death, late death and retire from society, was 47.1% in NYHA Class TV, and from 0 to 15.8% in NYHA Class I to Class III (p<0.01). 60 cases underwent valve replacement for infective endo-carditis, and 16 urgent operations were required in 23 active stage operations. Total early and late mortality was higher in active stage operation (30.0%) than in healed stage operation (2.7%) (p<0.01). In these way, the extension of the indications for operation was carried on the patients of advanced age, combined valve procedure for multiple valve disease, valve re-replacement and infective endocarditis. The operative risk was high in the patients older than 70 years old, the patients who had the risk factors of multiple organ failure after operation, valve re-replacement in NYHA Class IV, and the urgent operation at active stage of infective endocarditis.