Aorto-esophageal fistula is rare and frequently missed preoperatively, while catastrophic condition usually occurs in the event of massive upper gastrointestinal hemorrhage. Aorto-esophageal fistulas are generally caused by an aortic aneurysm, a previous operation, radiotherapy, or esophageal tumor. An 84-year-old woman suffered massive hematemesis from an aorto-esophageal fistula due to a previous esophageal ulcer. The diagnosis was confirmed by esophagogastroduodenoscopy, computed tomography, and angiography. An emergent aorta endovascular stent insertion was performed with initial hemostasis, but she died one day later due to multiple organ failure. Clinical outcome of aorto-esophageal fistula depends on early intervention before massive hemorrhage occurs. A high index of suspicion is needed for early diagnosis, which may improve the chance of survival.