BackgroundAortopulmonary window (APW) is a rare congenital cardiac anomaly characterized by communication between the main pulmonary artery and ascending aorta. There are various surgical techniques, and the short- and long-term results are excellent if the surgical repair is performed early in life. To our knowledge, there have been no reports of pseudoaneurysm after APW repair. Herein, we present a case of a 30-year-old woman with an ascending aortic pseudoaneurysm found at the site of APW repair nine months after the APW repair and bilateral lung transplantation.Case presentationsA 30-year-old woman presented with APW and Eisenmenger syndrome. The patient underwent APW repair and bilateral lung transplantation. We transected the communication between the aorta and pulmonary artery and closed the aortic side directly with strips of felts. Nine months after the surgery, the patient complained of chest pain. Cardiac computed tomography revealed an ascending aortic pseudoaneurysm at the anastomotic site. Emergent graft replacement of the ascending aorta was performed and the postoperative course was uneventful.ConclusionsWe have presented a case of a pseudoaneurysm at the anastomotic site after APW repair and bilateral lung transplantation. The choice of surgical technique should be based on the patient’s background requiring lung transplantation, and in these cases close postoperative follow-up is required.