The pseudo-aneurysms of thoracic aorta are rare and a life-threatening complication of aortic surgery and blunt chest trauma. This article demonstrates a case report of a traumatic aortic arch dissection and formation of a false aneurysm after blunt chest trauma in Iran. A 23-year-old man was referred complaining of chest pain and exertional cough. He had a history of chest and abdominal trauma five months ago after a car accident, resulting in acceleration-deceleration injury. The trauma resulted in an extensive injury on the left side of the chest and abdomen associated with multiple rib fractures, hemopneumothorax and splenic rupture. Splenectomy and left chest tube drainage was performed. The patient was admitted for 15 days. Finally, he recovered to normal and was discharged in satisfactory condition. However, his chest pain and cough restarted and its severity gradually increased. In chest x-ray, a left upper mediastinal mass was detected, which was later confirmed by 64 multi-slice chest CT scan as a false aortic arch aneurysm and aortic dissection. It seems endovascular stent-graft technique for the treatment of thoracic aorta aneurysm may present a good treatment choice with a low risk and less invasive approach.