The use of Guglielmi Detachable Coil (GDC) for the en do vascular treatment of intracerebral aneurysms is increasing, particularly in those aneurysms for which there is a high surgical morbidity and mortality. However, the long-term efficacy of GDC is not known. Until the natural history of GDC treatment is established longterm follow-up in this cohort of patients is required, of necessity involving repeated intraarterial angiography (IA DSA) with its known attendant risks and exposure to ionising radiation. Three dimensional time-of-flight magnetic resonance angiography (3D TOF MRA) is now readily accepted as a non-invasive screening tool for familial aneurysmal disease and has been used as an alternative to IA DSA in the surgical management of aneurysmal subarachnoid haemorrhage. MRA in patients treated with GDC is safe, imparts no radiation dose and provides acceptable image quality. The aim of this study was to assess 3D TOP MRA source data, maximum intensity projection (MIP) and 3D isosurface reconstruction in comparison to IA DSA in the follow-up of 25 patients treated with GDC. Images were assessed for parent and branch artery flow, the presence of neck recurrence and aneurysm regrowth. There was good correlation for all these features when 3D isosurface MRA and source data were compared with IA DSA. The correlation between MIP MRA and IA DSA was less robust. Additional confidence can be obtained by performing plain films of the skull to demonstrate change in coil ball configuration. MRA has the potential to replace IA DSA in the follow- up of GDC treated cerebral aneurysms.