A 23 year old Korean boy was admitted to Dept. of Neurosurgery, Capital Army Hospital on Feb. 2, 1971 beauseof recurrent transient focal seizure and motor weakness in the left extremities. During hospitalization, herecovered from focal seizure and motor weakness in the left extremities without specific therapy. Right carotidangiograms were performed. Right carotid angiogram show right internal carotic occlusion at the level of distalsiphon of extradural level with good filling of ophthalmic artery of right. Extensive small vacular networkdeveloped intracranial region of right hemisphere. There are appearance to be two major anastomotic communication.1. Via at the base of the brain. 2. Via the ret mirabile with external carotid artery. These angiographic findingswere similar to that of So-called :Cerebral rete mirabile" which was described in many literature. Etiology ofCerebral rete mirabile is divided as to whether these represent true congenital vascular malformations or whetherthe "rete mirabile" developes as a collateral because of a primary stenosis in the internal carotid arteris.Evidence for either theory is still inconclusive.