A chronic posttraumatic false aneurysm of descending aorta in a 19-year-old man who had been involved in a car accident 8 months earlier is described. He presented with chronic cough, and on chest roentgenogram, a mass in upper left mediastinum was noticed. Aortography and computed tomography scan revealed a false aneurysm of the descending aorta. The patient underwent aneurysm resection and graft replacement. Cough resolved after surgery and at 5 years follow-up the patient remained well and symptom-free.