A 23 year old Korean boy was admited to Dept. of Neurosurgery, Capital Army Hospital on Feb. 2, 1971 because of recurrent transient focal seizure and motor weakness in the left extremities. During hospitalization, he recovered from focal seizure and motor weakness in the left extremities without specific therapy. Right carotid angiograms were performed. Right carotid angiogram show right internal carotic occlusion at the level of distal siphon of extradural level with good filling of ophthalmic artery of right. Extensive small vacular network developed 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 findings were similar to that of the So-called "Cereberal rete mirabile" which was described in many literature. Etiolgy of cerebral rete mirabile is divided as to whether these represent ture congenital vascular malformations or whether the "rete mirabile" develops as a collateral because of a primary stenosis in the internal carotid arteries. Evidence for either theory is still inconclusive. still inconclusive.