Although the vertebrobasilar system accounts for up to 20% of the total cerebral blood flow and a proportionate share of strokes,1 many cases of vertebrobasilar disease remain undiagnosed or diagnosed incorrectly. Some common symptoms, such as dizziness or transient loss of consciousness, do not always prompt detailed examination of the posterior circulation vessels. A simple, fast, noninvasive ultrasound examination of the extra- and intracranial portions of the vertebrobasilar system can yield valuable information for diagnosis and treatment.2–10