Arteriovenous malformations (AVM's) of the medial temporal lobe frequently involve the basal ganglia and the thalamus and, for this reason, are commonly judged to be inoperable. However, when the medial involvement is limited to the posterolateral part of the thalamus and to the inferior portion of the basal ganglia lateral to the internal capsule, the lesions may be excised safely. Three patients who underwent successful excision of AVM's of this region are presented. A transcortical surgical approach through the inferior portion of the temporal lobe was used to minimize retraction of the temporal lobe and damage to the optic radiation, and to avoid postoperative dysphasia. The following neuroradiological criteria indicate that the bulk of the lesion is in the temporal lobe that only noncritical portions of the basal ganglia and thalamus are involved, and that therefore, surgical resection is relatively safe: 1) primary supply by the anterior choroidal artery and by laterally oriented branches of the posterior cerebral artery; 2) primary venous drainage into the basal vein of Rosenthal and medial Sylvian veins; 3) projection below the plane of the middle cerebral artery in the lateral carotid arteriogram; 4) projection lateral to the sweep of the posterior cerebral artery in the anteroposterior or Towne's view of te vertebral angiogram; and 5) demonstration of an intratemporal clot or intraventricular blood by computerized tomography.