Thoracic vertebral arteries are anastomotic chains similar to cervical vertebral arteries but found at the thoracic level. Descending thoracic vertebral arteries originate from the pretransverse segment of the cervical vertebral artery and curve caudally to pass into the last transverse foramen or the first costotransverse space. Ascending thoracic vertebral arteries originate from the aorta, pass through at least 1 costotransverse space, and continue cranially as the cervical vertebral artery. This report describes the angiographic anatomy and clinical significance of 9 cases of descending and 2 cases of ascending thoracic vertebral arteries. Being located within the upper costotransverse spaces, ascending and descending thoracic vertebral arteries can have important implications during spine interventional or surgical procedures. Because they frequently provide radiculomedullary or bronchial branches, they can also be involved in spinal cord ischemia, supply vascular malformations, or be an elusive source of hemoptysis.