Background: Aorto-pulmonary window is a rare heart disease occurring in 0.1-0.2% of patients with congenital cardiac disease and results from an incomplete development of the conotruncal septum. In half of the cases aorto-pulmonary windows are associated with other anomalies. This condition can occur on its own or with other heart defects such as: tetralogy of fallot, pulmonary atresia, atrial septal defect, interrupted aortic arch, truncus arteriosus, patent ductus arteriosus. Fifty percent of patients usually have no other heart defects. Babies that have a hole in between the aorta and pulmonary artery have blood from the aorta that flows into the pulmonary artery, and as a result too much blood flows to the lungs. This causes high blood pressure in the lungs (a condition called pulmonary hypertension) and congestive heart failure. Symptoms can include: delayed growth, irritability, rapid heartbeat, heart failure, infections of the lungs. Case: We describe a case of aortopulmonary window incidentally found during surgery for a Type A interrupted aortic arch and repaired uneventfully. Conclusions: In our case the anomaly was not diagnosed until the thoracotomy but anatomy allowed surgeon to perform the closure of the window.