Vessels present in the superior mediastinum are closely related and widely variable. Knowledge of their variation is necessary for cardiothoracic radiology and surgery. We present a case where left vertebral artery originated from the arch of the aorta and left subclavian artery had a narrowing at a site where a vein from the posterior thoracic wall had crossed it. This vein was found to be the accessory azygos vein which had communicated below with hemiazygos vein. The embryological and clinical implications of such a combination of vascular anomalies, probable cause of the narrowing of the subclavian artery are discussed.
