We describe a rare case of vertebral artery duplication in a patient with vertigo, weakness, and nausea. A color Doppler examination revealed a duplicate origin of the left vertebral artery and a hyperechoic thrombus at the origin of 1 of the duplicated arteries. CT angiography of the lower neck area demonstrated duplicated vertebral arteries on the left side. MR angiography of the vertebrobasilar system did not show duplication, indicating that the duplicated vertebral arteries fused at a level higher than C2. (C) 1998 John Wiley & Sons, Inc.