PURPOSE: To evaluate the usefulness, results, and technical problem of endovascular treatment in anteriorcommunicating artery(Acom) aneurysm using a Guglielmi detachable coil(GDC). MATERIALS AND METHODS: We evaluated 18patients with Acom aneurysm who underwent endovascular treat-ment with GDC. Their clinical presentations weresubarachnoid hemorrhage (n=14), decreased visual acuity (n=2), and remnant aneurysm after surgical clipping (n=2).Hunt and Hess grades of 16 pre-surgical patients were Grade 0 in two patients, Grade I in three, Grade II in five,Grade III in one, Grade IV in three and Grade V in two. The size of aneurysms was 20mm in one lesion that wasclassified as large, while other lesions with diameters ranging from 3 to 12mm were classified as small.Theoutcome of treatment and technical complica-tions were analyzed. Clinical results were evaluated using the Glasgowoutcome scale(GOS). RESULTS: Treatment was successful in 13 patients. Complete occlusion was observed in tenpatients and partial occlusion in three. In five patients, the procedure failed to occlude the aneurysms becauseof proximal arterial tortuousity (n=2), wide neck (n=2) or coil fracture during the procedure (n=1). Technicalcomplications in-cluded thromboembolism (n=1) and coil fracture during the procedure (n=1). Among the 13 patientswho were treated successfully, 11 were GOS I. Two patients died after treatment because of procedure-relatedthromboembolism in one patient and progressive vasospasm, demonstrated on angiography before treatment, in theother. CONCLUSIONS: Treatment of Acom aneurysm using a GDC is useful and has many advantages compared tosur-gical clipping. Because of the anatomical characteristics of the Acom, however, technical failure may be morelikely than in the case of posterior circulation aneurysm. Meticulous evaluation of aneurysms and adjacentar-teries on angiography, as well as careful patient selection, is needed.