This report describes successful therapeutic results of a huge and high flow arteriovenous malformation (AVM) in the left basal ganglionic region. A 39-year-old female was admitted to our hospital presenting recent progression of aphasia, hemianopsia, hemiparesis, hemisensory disturbance on the right side. Progression of disturbance in consciousness was rapid, and the patient became comatose shortly after admission. A CT scan revealed a densely enhanced lesion in the left basal ganglia which caused aqueductal obstruction and hydrocephalus. Angiography demonstrated a huge and high flow AVM that was supplied by the anterior and posterior choroidal arteries, the lateral striate arteries and the insular branches of the middle cerebral arteries. This AVM drained into the vein of Galen via the inferior ventricular and basal vein. The draining vein was markedly dilated at the level of midbrain by a prominent stenosis of the junction between the vein of Galen and straight sinus, and it severely compressed the midbrain. Superselective embolization of the feeding arteries was done in two sessions. This was followed by surgical intervention for the embolized AVM one month after the second session. Embolization and surgery were carried out under barbiturate protection to reduce the risk of normal perfusion pressure break-through. The patient recovered well from these interventions without any hemodynamic changes and showed dramatic improvement of all focal neurological abnormalities. Postoperative angiography showed only a small residue of AVM.