Acute esophageal necrosis (AEN) is a very rare disorder typically presenting as a diffuse black esophageal mucosa on upper endoscopy. For this reason, AEN is often considered to be synonymous with 'black esophagus'. The pathogenesis of entity is still unknown. We report a case of AEN with duodenal ulcer causing partial gastric outlet obstruction. A 53-year-old man presented with hematemesis after repeated vomiting. The upper gastrointestinal endoscopy revealed circumferential black coloration on middle 315 to lower esophageal mucosa that stopped abruptly at the gastroesophageal junction. Pyloric ring deformity and active duodenal ulceration with extensive edema was observed. After conservative management with NPO and intravenous proton pump inhibitor, he showed clinical and endoscopic improvement. He resumed an oral diet on day 7 and was discharged. In our case the main pathogenesis of disease could be accounted for massive esophageal reflux due to transient gastric outlet obstruction by duodenal ulcer and following local ischemic injury.