A 60-year-old man with effort angina and idiopathic thrombocytopenic purpura (ITP) underwent concomitant operation of coronary artery bypass grafting (CABG) and splenectomy. High-dose transvenous gamma-globulin therapy (400 mg/kg/day) was performed for five days before surgery. The platelet count increased from 1.4 X 10(4)/mm3 to 8.7 X 10(4)/mm3. CABG was performed immediately followed by splenectomy. This is the first case with concomitant operation of cardiac surgery and splenectomy which was safely performed after high-dose transvenous gamma-globulin therapy.