Cardiac surgery associated with idiopathic thrombocytopenic purpura (ITP) is rare, and only 10 cases have been reported in the literature. In this report, we described the successful surgical management of a patient with ITP, diabetes mellitus and malfunction of mitral bioprosthetic valve. A 62-year-old male, who underwent mitral valve replacement (MVR) by means of a Carpentier-Edwards valve prosthesis and CABG ten years ago, developed malfunction of mitral prosthetic valve. The preoperative platelet count was 52, 000/mm³ and PA-IgG elevated markedly. The diagnosis of ITP was based on findings of bone marrow examinations. Thrombocytopenia was treated by steroids for 4 weeks and large dose γ-globulin (20g/day) for 5 days preoperatively, but platelet count did not increase. Platelet rich plasma (PRP) was transfused prior to cardiopulmonary bypass (CPB) and fresh blood was added to the priming material of CPB. Re-MVR was performed by means of mechanical valve prosthesis. After operation, large doses of γ-globulin and transfusion of PRP were performed for 3 days, and the postoperative course was uneventful. Other reports in addition to this study reveal that cases of cardiac surgery associated with ITP should be initially controlled preoperatively with steroids or high-dose γ-globulin, and if these treatments are harmful or ineffective, splenectomy should be considered.