Currently, two treatment options are available for cerebral aneurysms: clipping and endovascular therapy(EVT). For patients with a ruptured aneurysm, superiority of endovascular coiling was reported by a randomized controlled trial(RCT). Therefore, it is important to know whether the patient has high risk factors for undergoing EVT. In addition, Also, we should know unavailability of adjunctive devices such as stents for ruptured cases. On the other hand, no RCT has reported the efficacy of clipping or EVT or compared treatment options for unruptured aneurysms. Therefore, the indication of treatment for unruptured cases is decided in a case-by-case manner according to the estimated rupture rate of the aneurysm based on data from large registries and institutional treatment complication rates. Introduction of various adjunctive devices such as stents, flow diverters, and bifurcation devices has widened indications of EVT for unruptured aneurysms. However, some patients are still at high risk for undergoing EVT despite the introduction of these devices. Since the superiority of these new devices has not been proven compared to traditional treatments, treatment should be carefully selected by taking aneurysmal and systemic factors into account.