Endovascular treatment of intracranial aneurysms is gaining an important development thanks to the further technical advances in catheters and occlusion materials (detachable and non detachable balloons). This treatment, performed under slight neuroleptanalgesia, allows access to the aneurysmal sac for selective occlusion with preservation of the parent vessel. In cases of fusiform or wide neck aneurysms, and if selective endosaccular occlusion is impossible or hazardous, the parent vessel occlusion can be performed with a test occlusion. Tolerance test occlusion of the parent vessel includes clinical monitoring, angiographic demonstration of good collateral supply and functional measures with local cerebral blood flux studies and transcranial doppler. This therapeutic approach is relatively simple in regard of neurosurgical treatment and allows improvement of the management of surgical high risk lesions.