BACKGROUND Aortoesophageal fistula is a rare etiology of serious gastrointestinal bleeding. Most aortoesophageal fistulas resulted from thoracic aortic aneurysms, foreign bodies, or esophageal malignancy. To our knowledge, spontaneous aortoesophageal fistula due to dermatomyositis and high dose steroid therapy has not been reported. CASE REPORT A 46-year-old Asian female with a history of dermatomyositis and duodenal ulcers presented with black stool for one day. She was initially admitted for dermatomyositis flare-up and received high dose steroid therapy. Four weeks after discharge, she experienced gastrointestinal bleeding from multiple duodenal ulcers. Due to a continuous fall in hemoglobin level, she received angiography and embolization to the gastroduodenal artery. After the procedure, the patient developed another episode of dermatomyositis flare-up and required endotracheal intubation. During ventilator weaning, she developed recurrent gastrointestinal bleeding. Repeated esophagogastroduodenoscopy showed one esophageal ulcer with active bleeding. Epinephrine hemostasis therapy was performed but with poor therapeutic response. Angiography showed no visible extravasation. Chest computed tomography with intravenous contrast revealed contrast extravasation in esophageal lumen with blood clots consistent with an aortoesophageal fistula. Despite our attempt to arrange an emergent endovascular stent, the patient went into cardiac arrest from circulatory collapse. CONCLUSIONS Dermatomyositis leads to esophageal structural abnormalities through various mechanisms. Aortoesophageal fistula is a life-threatening etiology of gastrointestinal bleeding and should be suspected if bleeding from an esophageal ulcer responds poorly to hemostatic treatment. Abdomen computed tomography with intravenous contrast is the preferred image modality for diagnosing aortoesophageal fistula. Thoracic endovascular aortic repair is a reasonable procedure to stop bleeding in patients with unstable hemodynamic profiles.