Tehran University of Medical Sciences Archives of Anesthesiology and Critical Care 2423-5849 8 3 2022 06 11 248 251 Pouran Hajian Department of Anesthesiology, School of Medicine, Clinical Research Development Unit of Beast Hospital, Hamadan University of Medical Sciences, Hamadan, Iran. Manoochehr Ghorbanpoor Department of Pediatric Surgery, School of Medicine, Clinical Research Development Unit of Beast Hospital, Hamadan University of Medical Sciences, Hamadan, Iran. Mahshid Nikooseresht Department of Anesthesiology, School of Medicine, Clinical Research Development Unit of Beast Hospital, Hamadan University of Medical Sciences, Hamadan, Iran. 2021 09 23 2021 10 18 Aortoesophageal Fistula (AEF) with no prior history of cardiac disease or trauma is an uncommon but a mortal cause of Upper Gastro Intestinal Bleeding (UGIB) in children. In pediatric patients, AEF is mainly due to a congenital cardiac or vascular anomaly or foreign body ingestion. There are surgical, endoscopic, and interventional radiological treatment options; however, definitive treatment is surgical intervention. Because of the rapid and devastating course, diagnosis and treatment decision should be made quickly. In this article, we report a case of an 11-months-old infant who presented with hematemesis due to a primary aortoesophageal fistula. The patient was transported to the operating theater for an emergency endoscopy. He suffered massive hematemesis in the operating room and an emergency laparotomy was performed but no source of bleeding was detected. An undiagnosed AEF was found and repaired during a left thoracotomy. Despite massive volume resuscitation, the patient passed away four hours later in the PICU. The etiology of the fistula remains unknown. https://aacc.tums.ac.ir/index.php/aacc/article/view/409