We analyzed clinical characteristics and surgical results in 44 patients aged 70 years or more with ruptured intracranial aneurysms operated on within 72 hours of hemorrhage. In comparison with a non-aged group of 264 patients aged less than 70 years (126 men and 138 women), the aged group (6 men and 36 women) showed a distinct female preponderance. The most common parent artery of ruptured aneurysm was the internal carotid artery in the aged group, while it was the anterior cerebral artery in the non-aged group. There. was no significant difference in the preoperative clinical grades (Hunt & Kosnik classification) between the two groups. Although delayed ischemic neurological deficit (DIND) appeared in both groups at almost the same frequencies, 32% and 34% for the aged and non-aged group, respectively, the incidence of permanent DIND was higher in the aged group (50%) than in the non-aged group (36%). The comparative studies on surgical results in each clinical grade revealed that outcomes of Grade IV patients were extremely poorer in the aged group (92% poor outcome) than those in the non-aged group (58% poor outcome, p=0.02). Although Grade III patients in the aged group also showed poorer outcomes, it did not reach statistical significance. Overall outcomes in a subgroup of patients aged 70-74 were almost the same as those in the non-aged group. Thus indications for early aneurysm surgery in aged patients, when their ages are under 75 and clinical grades below G III, are determined with the same standards as in non-aged patients. Among the factors accounting for poor outcome of each patient, the incidence of primary brain damage was higher in the aged group (53%) than that in the non-aged group (43%). These results indicate that the major cause of poor outcomes of aged patients is a poor recovery from brain damage due to either primary hemorrhage or symptomatic vasospasm.