The authors have dealt with six cases of spontaneous intracranial vertebral artery dissection during the past 3 years. Most of the patients were in their fourth or fifth decade of life, and men predominated. All except one patient had severe antecedent headache and half of the 6 cases were hypertensive. The presenting clinical features were subarachnoid hemorrhage, Wallenberg's syndrome, brain stem RIND(reversible ischemic neurologic deficit) and cerebellar infarct. The locations of the dissection were right vertebral artery in four patients, right vertebral and basilar artery in one and left vertebral artery in another one. Most of the patients showed typical intramural hematoma or double lumen on the MRI. In the MR angiography, irregular segmental narrowing of vertebral artery or invisible pathologic vertebral artery were demonstrated. The angiographic findings included alternating irregular stenotic and dilated segment(pearl and string sign), aneurysmal dilatation, occlusion etc. four patients were treated medically while the other two were treated surgically by proximal vertebral artery clipping of the affected artery. Upon follow-up, the outcome were excellent in two, good in two and fair in two.