Objective : This study is performed to evaluate the procedural complications, aneurysm occlusion rate, and mid-term outcome of endovascular treatments in intracranial aneurysms. Methods : We retrospectively investigated 135 patients with 161 cerebral aneurysms who were treated by endovascular means at our institute from March 1999 to December 2004. We statistically analyzed overall outcome, occlusion rate, and occurrence of complications according to the location, size, rupture history, and neck size of aneurysms. Results : Forty-nine patients [36.3%] had experienced acute intracranial or extracranial complications related to the procedure. Among these, there were 13cases of perforation of the aneurysm, 9 of local vasospasm, 8 of thromboembolism, 4 of coil migration, 3 of occlusion of parent vessels due to coil protrusion, and 1 of seizure. Extracranial complications occurred in 14cases including alopecia [9cases], femoral artery thrombosis [2cases], acute renal failure [2cases], and hypovolemic shock [1case]. One hundred twenty-six aneurysms [78.3%] had complete occlusion of the aneurysm and 35 [21.7%] incomplete occlusion at 6months angiographic follow-up. Postembolization clinical follow-up ranged from 1 to 60months [mean, 14.2months]. Seven of the 161 aneurysms underwent additional embolization and 2 incomplete embolized aneurysms required subsequent surgery. Conclusion : The procedural complications and incomplete occlusion rates are substantial. Therefore, endovascular treatment needs close and continued neurosurgical and neuroradiological concerns for the therapy of intracranial aneurysms.