We investigated immediate/late endoleaks and long-term patency following stent-graft placement for treatment of intracranial aneurysms located within the distal internal carotid artery (ICA) or vertebral artery (VA). Forty-five aneurysms in 41 patients receiving covered stents in three centres were followed. Outcome measures included aneurysm occlusion rate, endoleaks, late in-stent stenosis rate, clinical improvement, neurological deficiencies and death. Total aneurysm exclusion was achieved in 69.2% (n = 27), with 30.8% (n = 12) experiencing immediate residual endoleaks. Angiographic follow-up (mean 43.5 +/- 14.3 months) revealed that 87.2% (n = 34) were completely occluded with only 12.8% (n = 5) showing residual endoleaks. Predictors of immediate endoleaks in our patient group were stent number (P = 0.023) and stent diameter (P = 0.022), while predictors of late endoleaks in our patient group were stent diameter (P = 0.035) and stent angulation (P = 0.021). Late in-stent stenosis rates were 18.0 +/- 13.3 and 29.0 +/- 18.5% compared with the period immediately following implantation at 2- and 6-year follow-ups respectively. Smoking (P = 0.017) and stent angulation (P = 0.020) were predictors of late in-stent stenosis. Treating intracranial aneurysms with Willis stent-grafts has an acceptable immediate and late occlusion rate and long-term stented artery patency rate.