To evaluate the interest of 3D angiography in the diagnosis, treatment and follow-up of aneurysms with special regard with endovascular GDC treatment. Spin angiography with 44 subtracted views (512x512 image matrix) is first acquired with a rotation of a C-arm through 200 degrees at 40 degrees per second in an angiographic room prototype LCV+ single plane (GEMS). 3D reconstruction ART (Algebraic Reconstruction Technique) is automatically applied and interactive visualisation of the 3D angiography is available on a workstation (UltraSparc 2, Sun microsystems) 10 minutes after the spin angiography acquisition 30 angiography is displayed in MIP, surface rendering and endovascular views (virtual angioscopy). 52 2D and 3D angiographies were performed in 40 patients with 49 intracranial aneurysms whith the same protocol of acquisition (AP, lateral and spin angiography). Each 30 angiography (MIP and surface rendering) was analysed by 2 senior radiologists and compared with the corresponding 2D angiographies (AP, lateral and spin views). Artefacts due to GDC were present in 24 cases, but bothering in only 12 cases. Analysis of the aneurysm was better in MIP than in 20 in 32 cases, equivalent in 18 and worse in 2 due to patient movements during acquisition Surface rendering gave additional information in 29 cases. The impact was judged important for decision making or choice of treatment in 25 cases 30 angiography improves the analysis of the aneurysms, gives crucial information to make the decision for treatment and is now routinely used in our institution for the diagnosis of intracranial aneurysms and follow-up after GDC treatment.