Background Aneurysms with wide-necked or a large neck/fundus ratio, especially located on an arterial bifurcation or a small artery, are challenges for interventional neuroradiologist because of the risk of coil migration or coil protrusion into the parent vessels. Our study was designed to improve the efficacy and safety of the remodeling technique with the HyperForm balloon for these difficult aneurysms and was confirmed by a follow-up result. Methods From June 2004 to September 2006, forty-two patients(20 men, 22 women)with wide-necked or large neck/fundus ratio aneurysms were treated by using theremodeling techniquewith the HyperForm balloon. Results Forty wide-necked aneurysms were successfully treated with the HyperForm balloon remodeling technique with only two failed cases. Final results consisted of total occlusion in 34 cases(80.9%), subtotal in 4 (9.5%) and incomplete in 2(4.8%). One aneurysmal rupture occurred, but no clinical consequence was shown. No thromboembolic events were observed during treatment. Final angiographic follow-up time ranged from 3 to 18 months. Conclusions The remodeling technique with the HyperForm balloon is a very useful tool in the treatment of wide-necked or unfavorable neck/fundus ratio intracranial aneurysms-located on an arterial bifurcation or a small artery and, especially, located on the bifurcation of a large artery and a small one. In our experience, this technique provided a safe and efficient treatment for difficult aneurysms when the standard remodeling technique might have failed.