The CT findings of 98 patients with subarachnoid hemorrhage due to aneurysmal rupture were analysed and compared with cerebral angiography for the purpose of preangiographic prediction of aneurysmal loca-tion as well as evaluation of the CT features corresponding to the vasospasm or ischemic neurologic dysfunctions. The results were as follows. 1. Aneurysms could be identified on intial cerebral angiography in 82 out of 98 patients with subarachnoid hemorrhage and anterior communicating artery ICA basilar artery in order of frequency. 2. the CT findings of those patients were hemorrhage in subarachnoid space(69%) localized hematoma (47%) ventricular dilatation (31%) enhancing nodule (23%) cisternal enhancement(20%) cerebral infarction(15%) ventricular hemorrhage(14%) and epidural hemoorhage(3%) 3. Localized hematoma was more prevalent in anterior communicating artery aneurysm rupture(54%) and less frequently in MCA posterior communicating artery and ICA aneurysms. 4. Most of aneurysmal sac could be identified as enhancing nodule on CT when the real size were over 1 cm. 5. The site of ruptured aneurysm could be predicted in many patients with ACA and MCA aneurysm accor-ding to the CT features such as hemorrhagic patterns location of hematomas or enhancing nodules. 6. Localized hematoma or blood clots and cerebral infarction are considered to be the CT features correspon-ding to the angiographic vasospasm.