The case of a 720-g infant born at 29 weeks of gestation who underwent successful surgical correction of a hypoplastic aortic arch and aortic coarctation is presented. The infant was initially brought to surgery with an echocardiographic diagnosis of patent ductus arteriosus with left to right shunt unresponsive to indomethacin therapy. The correct diagnosis of hypoplastic aortic arch and severe coarctation with ductal dependent blood flow to the lower body was made intraoperatively. This case illustrates the danger of limited diagnostic testing in premature infants assumed to have isolated patent ductus arteriosus, and also that these small infants can undergo successful surgical repair of complex aortic arch lesions.