We report a rare case of presumed post-traumatic aortic arch aneurysm complicated by an aorto-pulmonary artery fistula. Contrast-enhanced computed tomographic pulmonary angiography completed by dynamic cardiac magnetic resonance imaging allowed adequate preoperative visualization of an 8-mm large fistula between the aneurysm and the left pulmonary artery. The patient underwent successful total aortic arch replacement and closure of the fistula using a patch.