We have experienced 20 cases of the cerebral rete mirabile from 1969 to 1975. All were proved by bilateral carotid angiography, and clinical assessment and angiographical analysis were attempted. The results were summarized as follows: 1. Age distribution was ranged from 5 to 55. The majority of 20 cases were age over 20 as 15 cases who were distributed evenly in each decade and 5 cases were age below 20. 12 cases were male and 8 female. 2. Authors classified the cases as the group of subarachnoid hemorrhage and non-subarachnoid hemorrhage conveniently. All cases of age below 20 comprised in the group of non-subarachnoid hemorrhage while majority of subarachnoid hemorrhage group were age over 20. 3. There were no contributory factors to cerebral rete mirabile with regard to past history and family background. 4. There were considerable differences in the symptoms and signs between the groups of subarachnoid hemorrhage and non-subarachnoid hemorrhage. Clinical manifestations were mainly headache and impairment of consciousness with meningeal sign in the group of subarachnoid hemorrhage. On the other hand, motor disturbance such as hemiparesis or monoparesis was occurred in the majority of non-subarachnoid hemorrhage and the minority showed speech impairment, seizure and choreiform movement. 5. All cases showed the characteristic angiographic findings of cerebral rete mirabile, which are occlusion or stenosis at the supraclinoid portion of internal carotid artery with abnormal fine vascular network around the base of brain and poor or non-visualizing anterior cerebral and middle cerebral arteries. The interesting picture was rete formation of ophthalmic artery in the orbit of 2 cases. There were no abnormal angiographic findings on the vertebral angiogram except retrograde filling to anterior cerebral and middle cerebral arteries through collateral channel from the posterior cerebral artery. 6. The prognosis of the cerebral rete mirabile seem to be favorable with regard to mortality. There were no death in our 20 cases during the period of observation.