We reported a case of ITP associated with chronic subdural hematoma. A 51-year-old female was admitted to our hospital with left frontal pain on November 18, 1995. CT and MRI examinations revealed a left chronic subdural hematoma. Peripheral platelet count showed thrombocytopenia, 5,000/mm3. She was treated preoperatively by administration of steroids, a large dose of immunoglobulin and transfusion of platelet. Five days after admission, platelet count had elevated to 199,000/mm3, and evacuation of the hematoma through a burr hole under local anesthesia was performed successfully. No troubles were observed during and after surgical procedure. Intracerebral hemorrhages associated with coagulopathy are rather common, but only 6 cases of ITP associated with chronic subdural hematoma have been reported. The characteristic clinical features and treatment of these 6 cases including our own case was noted. The cases of patients less than 40 years old were usually treated by emergency operation with transfusion of platelet because of severe neurological deficits. However, in the cases of patients over 40 years old treated by elected operation after administration of steroids, a large dose of immunoglobulin and transfusion of platelet did not give rise to severe neurological deficits. Therefore, we emphasize that the treatment against thrombocytopenia should be recommended taking the age of patients into consideration.