This study evaluated the clinical and angiographic outcome of large aneurysms treated with coil embolization at an acute stage in patients with poor-grade subarachnoid hemorrhage (SAH). Between July 1, 2001 and June 30, 2004, eight consecutive WFNS grade 5 patients with large aneurysms (15~23 mm) were treated with endovascular coil embolization within two days and followed for at least 30 months. There were three middle cerebral and five internal carotid artery aneurysms. No patients were treated by craniotomy and none survived without treatment. Two patients died of primary brain damage or cerebral vasospasm within one month. One patient died of pneumonia at 24 months. Four patients were alive with good recovery or moderate disability at the time of final follow-up (30~66 months). Angiography immediately after the procedure showed complete occlusion in three, neck remnant in four, and body filling in one patient. No complication was seen related to the procedure. Three aneurysms that were initially neck remnant developed body filling due to coil compaction. Two were re-treated with coils at six and 12 months and resulted in neck remnant. One patient refused re-treatment and died of re-bleeding. Endovascular coil embolization can be selected at an acute stage for the treatment of aneurysms in patients with poor-grade SAH without intraparenchymal hematoma even if the aneur-ysm is large. Serial follow up by MRA/angiography is necessary for at least 12 months.