The aim of this study was to evaluate endovascular treatment of anterior communicating artery aneurysms using Guglielmi detachable coils GDC. To obtain long-term follow-up, we selected patients treated between October 1992 and March 1994. Among the 251 berry aneurysms treated by detachable coils at our institution, 36 were located at the anterior communicating artery and treated with GDC. The most frequent clinical presentation in this group (86%) was subarachnoid haemorrhage (30 cases). There were 23 aneurysms which were completely and 6 were partially occluded. We did not treat 7 aneurysms. In 3 cases, no endovascular treatment was attempted either because the aneurysmal neck was not clearly distinct from the adjacent, or parent vessels (2 cases), or because the aneurysm sac was too small (1 case). In 4 cases, treatment failed because of atheroma of the cervical and intracranial vessels. Complications were, in the majority of cases, related to clotting (3 cases) with a good outcome in 2 cases and neurological sequelae in 1. In 1 case rupture of the aneurysm occurred during treatment. Endovascular packing was continued until complete occlusion of the aneurysm was achieved and no clinical complication was observed after the treatment. Two patients died as a result of complications of subarachnoid haemorrhage (vasospasm in one case, pulmonary complications in the other). Endovascular treatment using GDC is an efficient technique for treating anterior communicating artery aneurysms even in the acute phase of bleeding.