A 64-year-old man underwent vascular graft surgery for an abdominal aortic aneurysm one year previously. Using esophagogastroduodenoscopy (EGD), he was definitively diagnosed as having an aortoenteric fistula (AEF) and underwent an urgent surgical procedure for treatment. Generally, the prognosis in cases of AEF after vascular graft operation remains poor, and the survival rate in cases of AEF that require surgery is low. We report this case of AEF because EGD played a significant role in its early detection and definitive diagnosis, which resulted in the patient’s survival. EGD is not a common procedure for patients with severe symptoms. Therefore, it is necessary to accumulate and analyze data on more cases concerning the criteria for adoption of EGD, which will allow for a more accurate and timely AEF diagnosis in the future.