Nine patients with bilateral occlusions of the distal vertebral arteries had clinical profiles that differed from patients with other vertebrobasilar lesions and formed a recognizable subunit. Bilateral distal vertebral artery occlusion is uncommon; it occurs primarily in hypertensive patients, and neurologic deficits develop progressively or stepwise over a longer time period than in basilar artery or branch occlusion. It causes mostly cerebellar and lower brainstem signs as a result of chronic low flow in the posterior circulation; it may cause sudden respiratory death. The prognosis is grave. Anticoagulant therapy alone is probably ineffective.