A 65-year-old female visited the emergency room due to sudden hematemesis and hematochezia. One year earlier, the patient underwent endovascular implantation of an aorto-bi-iliac bifurcation stent graft for a fusiform infrarenal aortic aneurysm that extended to the left common iliac artery. At the time of presentation, her blood pressure and heart rate were 70/40 mmHg and 105 beats/min, respectively. Laboratory findings showed a white blood cell count of 13,000/μL, hemoglobin level of 8.0 g/dL, and platelet count of 405,000/μL. Emergent endoscopy identified a foreign material (an aortic stent graft) with vascular pulsation in the third part of the duodenum (Fig. 1). Abdominal computed tomography revealed increased fat stranding around the aorta, which is indicative of inflammation, and a loss of the fat plane between the duodenum and aorta (Fig. 2). Therefore, the cause of bleeding was diagnosed as an aortoduodenal fistula caused by the previously placed aortic stent graft. The patient underwent primary closure of the duodenal perforation and omental wrapping and was discharged without any complications. However, the patient passed away 31 months later due to recurrence of the aortoduodenal fistula.