A 64 year-old woman was transferred from the psychiatry department to the nenrosurgery on Mar, 1974. Her principal complaints were long standing headache, frequent grandmal seizure and episodic dysarthria. The present illness began in Dec. 1969, about 6 years before admission, with severe headache radiating from the occipital region to the temporal and facial region, drowsy mentallity and bilateral papilledema. Examination of the visual fields showed 3 diopters papilledema and no visual disturbance. The plain skull films revealed a hen egg-sized cloudy, partly denser, and partly strand-like calcific mass in the left frontal lobe area. Left carotid angiogram revealed smooth rightward displacement toward the affected side of the anterior cerebral artery and lateral and downward displacement of the knee portion of the middle cerebral artery. Lateral view showed slight downward depression of the anterior portion of the sylvian triangle and of the anterior cerebral artery. There wa no tumor staining. Conray ventriculogram showed collapse of the anterior horn of the lateral ventricle and rightward displacement of the 3rd ventricle and septum pellicidum in A-P view. Lateral film showed depression of the anterior horn with nodular filling defects along the lateral ventricle. The tumor was removed radically and the pathology turned out to be oligodendroglioma.