We investigated the role of GDC embolization as a second choice for the treatment of ruptured cerebral aneurysm. From september 1997 to may 2001, 139 ruptured aneurysms out of 151 consecutive ruptured aneurysms transferred to our hospital were treated by clipping (first choice) or GDC embolization (second choice). Patient selection was decided by more than two neurosurgeons under the policy that GDC embolization is the second choice of treatment. The mid-term (longer than three months) outcome of both group was examined. One hundred and nineteen Ans (BA two, IC-paraclinoid one, IC-PC or IC-Ach 36, IC-ant. Wall two, ACoA34, ACA six, MCA38) were treated by clipping (clipping group), 20 Ans (surgical difficulty; BA three, IC-paraclinoid three, VA dissection six, general complications; IC-PC two, IC-dissection one, ACoA four, VAPICA one) by GDC embolization (GDC group) within 24 hours after admission. SAH grade and GOS of each group were Gr1: 35&4, Gr2: 41&5, Gr3: 23&5, Gr4: 11&4, Gr5: 9&2, respectively, and GR: 79&14, MD: 8&3, SD: 11&0, VS: 8&0, D: 13&3 respectively. Good prognosis (better than MD) was gained in 73% of clipping group and 85% of GDC group. No rebleeding was seen in GDC group. GDC embolization for the cases with surgical difficulty or general complication raised the overall outcome. GDC embolization would be suitable for IC-paraclinoid Ans, BA-VA Ans, and ruptured VA dissections. Because of the good clinical outcome gained in the GDC group, GDC treatment would be the first choice of treatment for such aneurysms as geometrically suitable for coiling.