CT scan has made a new epoch in the diagnosis of intracranial diseases in 1970's , but so far as intracranial aneurysms, angiography is the last and conclusive method of the diagnosis as yet. When the disease is confirmed by cerebral angiography, it can be curable or preventable for the recurrency by surgical method. We have analysed 50 cases who were admitted to Seoul National University Hospital from Jan. 1974 to Aug. 1978 and proved to have aneurysm by cerbral angiography. The results are as follows; 1. Sex ratio was 1:1 and the most prevalent age group was in fourth fifth and sixth decades (76%). Headache and disturbances of consciousness were the most common symptoms(80%), and nausea and vomiting were also common symptoms. Hypertension was noted in 36% of them. 2. Mostcommon site of anerysms was the anterior cerebral artery-anterior communicating artery group (46.3%), 27.8% on internal carotid artery-posterior communicating artery group, 24.1% on middle cerebral artery. 1.8% on posteriorcerebral artery. 3. Three (6%) multiple aneruysms were noted and all were associated with posterior communicating artery aneruysms. 4. We had one case of unruptured symptomatic aneruysms located on anterior communicating artery.5. We performed 4 vessel study most frequently (485), unilateral carotid angiogram on 22%, bilateral carotidangiogram on 30%. The measurement of aneurysm size in angiography showed 48% in 3-5mm, 6-10mm and over 10mm are 26% respectively. Angiographically, spasm in parent artery was found most frequently(44%). localized arterialspasm in 20%, generalized in 18%. 6. Intracerebral hematoma associated with ruptured aneurysms were 12 cases(24%). 7. Arteriosclerotic change demonstrated in 2 cases (4%) angiographically, and ruptured aneurysms associated with hydrocephalus was found in 4 cases (8%). 8. Aneurysmal sac with smooth aneurysmal margin was found in 17cases (34%), and irregular, faintly outlined margin in 33 cases (66%). Loculated aneurysmal sac was noticed in 9cases (18%), and 5 cases of them were 2 loculations. 4 cases of them 3 loculations. We had one mycotic anerysm onleft distal middle cerebral artery, with 3 large loculations and delyed visualization of aneurysmal sac, and the evidence of hematoma, proved by pathology. 9. Post-operative angiography was done in 13 cases (26%), and 4 cases of them shown constant visualization of sac like preoperative findings. 10. Clinically, blood pressure and neurological conditions on admission and angiographically, the extents of arterial spasm, size of aneruysms and the presence of the intracranial hematoma were influenced the prognosis of tee patient. 11. In addition to the standard views (A-P, Lateral) for carotid angiography, specific projections are valuable for the demonstration of aneurysms invarious site. 12. In 98% of all cases, simple skull findings are normal, in 2 cases, CT scan was performed and only one case was compatible with the findings of aneruysmal rupture.