Objective To evaluate the mid- and long-term radiological outcomes of cerebral aneurysms with GDCs embolization.Methods One hundred and sixty-two patients with 173 aneurysms embolized with GDCs underwent angiographic follow-up from 1 to 54 months post-operatively and were retrospectively reviewed. Three neuro-radiologists reviewed each angiogram and made a comparison between initial and follow-up angiograms. Morphological outcomes were evaluated as follows: unchanged; progressive thrombosis; and re-opening or re-growth. Results Of 173 aneurysms with GDC embolization, 142 aneutysms had total or nearly total occlusion, 23 subtotal occlusion and 8 partial occlusion shown on initial angiograms. The incidence of re-opening was 17.1% (13/76) in less than 3 months, and 6.2% (6/97) between 3 and 6 months postoperatively. Four aneurysms showed recurrency(2.3%) on second follow-up angiography in one year after procedure and one-year cumulative recurrent rate was 13.3% of 56 aneurysms with the third follow-up angiography in the post-operation period of 12 to 54 months, four showed a little enlargement and the cmnulative recurrent rate so far was 20.2% (35/173). Conclusions The direct and main causes for aneurysmal recurrence are incomplete and loosening packing. The first angiographic follow-up is recommended to be performed at 3 months or earlier after the procedure, especially in aneurysms with initial incomplete occlusion. Re-treatment with balloon- or stent-assisted coil embolization is recommended in re-opening aneurysms. (J Intervent Radiol,2005,14:472-479)