We propose this combined balloon occlusion and surgical technique to treat selected patients with large-giant aneurysms not suitable for a pure endovascular or surgical approach. After an occlusion test a non detachable balloon catheter is positioned deflated proximally to the neck of the aneurysm under general anesthesia. The patient is then moved to the neurosurgical room. During the intervention the balloon is inflated and deflated when necessary to allow better surgical control of the aneurysmal sac. With this approach we achieve complete aneurysm occlusion and shorten the surgery time. Since January 2003 we have treated 13 giant aneurysms (ten paraclinoid and three vertebrobasilar) without significant complications related to balloon assistance and a good outcome in all patients.