After critically reviewing the last 50 years' literature pertaining to vertebrobasilar insufficiency, we reached the following conclusions: One can seldom accurately localize vascular pathologic lesions in the posterior circulation by clinical examination alone. The symptoms of vertebrobasilar insufficiency have multiple causes. Stenotic and occlusive lesions have been found at every level of the vertebrobasilar circulation. Currently, a complete investigation requires four-vessel cerebral angiography. No therapeutic modality, medical or surgical, has been proved unequivocably to be of benefit. New surgical approaches to the vertebrobasilar circulation that show promise in providing alternative methods of treatment have been developed.