Aim: The aim of this study was to present the clinical and angiographic outcomes of A1 aneurysms treated by coil embolization. Materials and Methods: We retrospectively evaluated 38 consecutive patients with A1 aneurysm (20 ruptured and 18 unruptured; mean age, 53.8 +/- 11.9 years) from 2011 to 2014 treated by an endovascular approach in our hospital. Follow-up angiography was obtained in 30 patients. Clinical outcomes were evaluated by modified Rankin Scale (mRS) over telephone. Results: Among the 38 patients, 24 were treated with single-catheter technique, 8 with stent-assisted coiling (Enterprise 3; Solitaire 5), 5 with parent vessel obliteration, and 1 with balloon-assisted coiling. Initial angiographic results revealed that complete occlusion was achieved in 21 aneurysms (55.3%), near-complete occlusion in 16 (42.1%), and partial occlusion with contrast agent filling the aneurysm sac in 1 (2.6%). Procedure-related complications were observed in 6 patients (15.8%). Follow-up angiographic imaging evaluation after coil embolization was performed in 32 aneurysms (mean interval, 22.6 +/- 6.7 months), which showed that 31 (96.9%) aneurysms remained stable or improved without regrowth, while minor recanalization was found in 1 aneurysm (3.1%), which was treated by parent vessel occlusion. Clinical follow-up evaluation was excellent in 37 of the 38 patients (mRS score 0 in 34, and mRS score 1 in 3) at a mean duration of 26.6 +/- 7.7 months. Conclusions: Endovascular treatment is feasible and effective for A1 segment aneurysms. The current treatment selections, including single-catheter embolization, balloon-assisted coiling, stent-assisted coiling, and parent vessel occlusion, should be performed according to the characteristics and morphology of A1 aneurysms.