&NA;Two patients with xanthogranuloma of the 3rd ventricle are described. In each instance the tumor obstructed the interventricular foramina and caused dilatation of the lateral ventricles and signs of increased intracranial pressure; computerized tomography demonstrated the dense, nonenhancing lesion in the anterior 3rd ventricle. The pathogenesis of these rare tumors is discussed. These cases affirm the need to consider xanthogranuloma in the differential diagnosis of anterior 3rd ventricle tumors in adults.