The authors describe a case of giant fusiform aneurysm of the basilar artery presenting with ischemic symptoms. Angiography and CT revealed vertebro-basilar fusiform aneurysmal dilatation. Fusiform vertebro-basilar aneurysm is associated with various complications particularly brain stem infarction. Similar lesions in the literature are reviewed and the relationship between this clinical entity and cerebral ischemia, particularly brain-stem infarction are discussed.