Persistent left fifth aortic arch is a rare anomaly often associated with aortic coarctation. We report the case of a newborn presenting with signs of duct-dependent aortic coarctation. Echocardiography showed an interrupted fourth aortic arch, persistent left fifth aortic arch associated with aortic coarctation, and a restrictive arterial duct. Arch repair was accomplished using the fifth aortic arch as an in situ flap to enlarge the hypoplastic fourth aortic arch associated with coarctectomy and extended end-to-end anastomosis. We believe that this newly reported surgical approach is safe and effective and allows for adequate enlargement of the entire fourth aortic arch. (C) 2017 by The Society of Thoracic Surgeons