In posterior circulation aneurysms, GDC endosaccular occlusion is the treatment of choice, when indicated. This report assessed anatomical, morphological and clinical criteria in the choice of vertebral or basilar artery occlusion in posterior circulation aneurysms, when GDC endosaccular treatment, with or without the "remodelling technique", is not indicated, as in giant or wide-neck aneurysms. Over five years we observed eleven patients harboring posterior circulation aneurysms with no indication for treatment with GDC, or only vertebral occlusion. In our experience, the endovascular occlusion of a single or both vertebral arteries or basilar artery, following a detailed anatomical and clinical assessment, has proved a good, reliable treatment in large or giant vertebrobasilar aneurysms or those without a neck.