Five patients with spontaneous dissecting vertebral aneurysms presenting with subarachnoid hemorrhage were treated with endovascular proximal balloon occlusion after a successful balloon Matas' test. Occlusion was performed in the extracranial portion of the vertebral artery after the potentially dangerous period of cerebral vasospasm. Two patients rebled preoperatively during the waiting period. Although angiograms demonstrated residual aneurysmal dilatation for four of the five patients, postoperative hemorrhages or progression of the dissection were not observed during the 19- to 48-month follow-up period. Only one patient experienced transient postoperative ischemic complication. Although the timing of the procedure and the site of occlusion remain controversial, proximal balloon occlusion of the vertebral artery appears to be a safe and effective therapy for patients with dissecting vertebral aneurysms presenting with subarachnoid hemorrhages. This method provides an important, less invasive alternative for this condition.