We report a case of a patient with a double-primary aortoenteric fistula with an abdominal aortic aneurysm. A 75-year-old man was taken to the operating room for the repair of an abdominal aortic aneurysm and a suspected aortoenteric fistula between the aorta and sigmoid colon. Sudden onset of massive bleeding through the nasogastric tube occurred after the induction of anesthesia. Surgical exploration confirmed an unexpected aortoduodenal fistula. Primary aortoenteric fistula is extremely rare and difficult to diagnose, and may cause fatal bleeding. The possibility of the presence of aortoenteric fistula, including multiple types, should be considered in the anesthetic management of abdominal aortic aneurysm.