Dissection of either the internal carotid artery or the vertebral artery (cervicocephalic arterial dissection) was once considered uncommon. However, in the past few decades, it has been increasingly recognized as a cause of stroke in young and middle-aged adults. Dissection causes only 0.4-2.5% of all strokes in the general population but causes 5-20% of strokes among young patients. Anticoagulant therapy is usually started immediately after the dissection is diagnosed. The clinical and radiologic features are important to recognize so that anticoagulation therapy can be started promptly, thereby minimizing the risks of infarction, permanent neurologic disability, and death.