Objective : Many vascular neurosurgeons tend to remove bone flap in patients with large aneurysmal intracerebral hematomas (ICH). However, relatively little work has been done regarding the effectiveness of prophylactic decompressive craniectomy in a patient with a large aneurysmal ICH. Methods : Large ICH was defined as hematoma when its volume exceeded 25 mL, ipsilateral to aneurysms. The patients were divided into two groups; aneurysmal subarachnoid hemorrhage (SAH) associated with large ICH, January, 1994 - December, 1999 (Group A, 41 patients), aneurysmal SAH associated with large ICH, January, 2000 - May, 2005 (Group 8, 27 patients). Demographic and clinical variables including age, sex, hypertension, vasospasm, rebleeding, Hunt-Hess grade, aneurysm location, aneurysm size, and outcome were compared between two groups, and also compared between craniotomy and craniectomy patients in Group A. Results : In Group A. 21 of 41 patients underwent prophylactic decompressive craniectomy. In Group 8, only two patients underwent craniectomy. Surgical outcome in Group A (good 23, poor 18) was statistically not different from Group 8 (good 15, poor 12). Surgical outcomes between craniectomy (good 12, poor 9) and craniotomy cases (good 11, poor 9) in Group A were also comparable. Conclusion : We recommend that a craniotomy can be carried out safely without prophylactic craniectomy in patients with a large aneurysmal ICH if intracranial pressure is controllable with hematoma evacuation.