Spontaneous dissections of the carotid and vertebral arteries in the neck are a common cause of stroke in young and middle-aged people. Moreover, they are increasingly recognized as the cause of a wide variety of other, more subtle, neurologic signs and symptoms. The cause of these arterial dissections largely remains unexplained but probably involves a combination of genetic and environmental factors. Magnetic resonance imaging has largely surpassed angiography as the imaging study of choice. The treatment of carotid and vertebral artery dissections is based on rather incomplete evidence. Anticoagulation with heparin followed by warfarin remains the treatment of choice in most major medical centers and is supported by the demonstration of emboli as the most common cause of stroke in these patients. The burgeoning interest in endovascular techniques has resulted in many patients being treated for carotid and vertebral artery dissections with percutaneous angioplasty and stent deployment. Although the treatment of dissections is generally well tolerated and the radiographic results are impressive, most dissections heal spontaneously and the associated aneurysms never rupture and rarely cause delayed ischemic symptoms. Surgical treatment of dissections, consisting of an in situ interposition graft or extracranial-intracranial bypass, is indicated only for those patients with persistent symptoms refractory to maximal medical therapy who are not candidates for endovascular treatment.