The clinical manifestations presented by 83 patients with intracranial aneurysms are reviewed. The site of the aneurysms were: 41 in the internal carotid, 19 in the middle cerebral, 19 in the anterior cerebral and 4 in the basilar artery. Rebleeding occurred in 17 cases; 12 of these patients died, Intracranial surgery was undertaken in 27 cases of aneuysms of the carotid, 14 the middle cerebral and 8 of the anterior cerebral artery. Seven patients were treated by occlusion of the internal carotid in the neck. Surgical mortality was of 37% among the cases of aneurysms of the carotid, of 28,5% among the middle cerebral artery cases and of 50% in those with aneurysms in the anterior cerebral artery system. There was no post-operatory death in the patients whose carotid arteries were occluded. Mortality was of 12% among the cases with aneurysms of the carotid, of 20% in the middle cerebral and of 50% in the anterior cerebral artery cases. Continuous spinal drainage during surgery with the patients in sitting positions was undertaken in 19 patients with good results. In 16 patients post-operative angiograms were performed.