A 1-month-old patient was brought to our institution with clinical signs of pulmonary hypertension. Cross-sectional echocardiography suggested a diagnosis of aortopulmonary window. At the time of surgery, we found that the right pulmonary artery was arising anomalously from the left side of the ascending aorta, but was also connected to the pulmonary trunk by a fibrous cord. We reimplanted the right pulmonary artery into the pulmonary trunk, closing the resultant opening in the ascending aorta by direct suture. The postoperative course was uneventful. On follow-up, the patient is asymptomatic without medication.