This report is on 19 patients with vertebrobasilar insufficiency in whom direct extra-intracranial arterial bypass surgery to the posterior circulation was performed. In all patients preoperative angiography had demonstrated vascular lesions of haemodynamic significance of either one or both vertebral arteries (VA) or within the vertebral-basilar artery junction (VABAJ). The bypass procedure was performed between the occipital artery (OA) and - depending on the localization of the obstructive vascular lesion - the posterior inferior cerebellar artery (PICA), the VA or the anterior inferior cerebellar artery (AICA). A modification of the operative technique is presented with using a paramedian approach. The clinical results of this series support the concept that a patent extra-intracranial graft to the posterior circulation may have a protective effect by preventing further ischaemic events.