A case of nontraumatic chronic subdural hematoma due to obstruction of dural vessels by tumor cells is presented and 25 reported cases are reviewed. A 39-year-old female was referred for headache, vomiting, disturbance of consciousness and right homonymous hemianopia with macular sparing. She had undergone mammectomy for medullary nodular carcinoma of the left breast five years before. She had been treated with combined hormonal therapy and chemotherapy for the cancer metastases to the liver in preceeding six months. Hematological examination revealed drug-induced thrombocytopenia, increase of FDP in blood (80 micrograms/ml), but no abnormality of prothrombin time and fibrinogen content. Therefore in the present case there was no evidence of disseminated intravascular coagulation (DIC) after Colman's criteria. However, it was suggested that this case had compensated DIC after Cooper's criteria. CT scan showed a biconvex-shaped low and partially iso-density area over the left fronto-temporal convexity, indicative of chronic subdural hematoma, and no abnormal findings in the occipital area. After removal of the hematoma she became alert without headache and vomiting. However, seven days later she complained of headache and vomiting again. Repeated CT scan showed a larger biconvex-shaped low density area over the left hemisphere extending to the parietal region at that time. Second operation was performed, but she expired four days later. Autopsy showed systemic metastases of the medullary nodular carcinoma in the scalp, temporal muscle and dura as well as lungs, adrenal glands, ovaries and bone marrow.(ABSTRACT TRUNCATED AT 250 WORDS)