To formulate treatment strategies for poor-grade patients after aneurysmal subarachnoid hemorrhage (SAH), medical records were analyzed for 166 patients who were in Hunt and Hess Grade IV or V among 588 consecutive cases with ruptured intracranial aneurysm admitted during the past 5 years. Causes of unfavorable outcome (poor or dead) in those 166 patients were evaluated to improve the management outcome. Overall management results of the 166 poor-grade patients were favorable (good or fair) in 71 (42.8%), unfavorable in 95 (78 dead, 17 poor). Direct clipping was performed in 90 patients, and the results were favorable in 69 (76.7%) and unfavorable in 21 (23.3%). Surgery was not done in 76 patients because 41 were moribund on arrival, 15 deterioration due to rebleeding, 7 severe brain swelling, 5 serious medical illness, one severe delayed ischemic deficit (DID), and one cerebral infarction following angiography, and 6 refused surgery. Seven patients survived in non-surgery group (2 fair, 5 poor). Direct effects of aneurysm rupture (34.8%) and early rebleeding (34.8%) were the major causes of unfavorable outcome in Grade IV patients, while it was direct effect of aneurysm rupture (91.8%) in Grade V patients. It is suggested that as rebleeding is the only preventable cause of unfavorable outcome, urgent management is necessary to prevent rebleeding, especially for Grade IV patients. Grade IV patients should be treated aggressively with direct clipping for non-complex aneurysms or for patients with hematoma, and coil embolization for complex aneurysms without hematoma.