A 71-year-old male was admitted to our hospital because of a chest abnormal shadow. His chest X-ray film showed a mass in the right lower lobe (S6), which was diagnosed as adenocarcinoma by transbronchial lung biopsy. A lab data on the admission showed thrombocytopenia (44,000 per cu. mm), and the results of the bone marrow aspiration was compatible with idiopathic thrombocytopenic purpura. Immediately after the right lower lobectomy with lymphnode dissection, intrathoracic bleeding from the wound due to hemorrhagic tendency appeared necessitating a re-thoracotomy. High-dose intravenous gamma-globulin infusion for 4 days and the frequent concentrated platelet transfusion were employed to prevent the hemorrhagic tendency after the 2nd operation, and the postoperative hemorrhage was successfully controlled. Perioperative high-dose intravenous gamma-globulin infusion was concluded to be useful in the patient of idiopathic thrombocytopenic purpura for preventing hemorrhagic tendency after the operation.