A 63-year-old woman with type 2 diabetes presented to the emergency department with a 2-day history of hematemesis and black stool. Esophagogastroduodenoscopy (EGD) revealed a black esophagus with ulcerated longitudinal necrosis in the lower esophagus (Panel A), findings that were consistent with acute esophageal necrosis. The cause of acute esophageal necrosis is unknown, although it may be associated with the presence of an underlying chronic disease such as cancer, cirrhosis, alcohol-use disorder, or chronic kidney disease. Acute esophageal necrosis occurs most commonly in the distal third of the esophagus, which is hypovascular as compared with other segments. The patient was treated conservatively with restriction of oral intake and treatment with a proton-pump inhibitor to reduce the risk of further acid-induced injury. Esophageal perforation is a potential acute complication of acute esophageal necrosis, and the development of esophageal strictures can be a longer-term complication. The patient’s condition improved and she had no complications; she was discharged 10 days after admission. Follow-up EGD that was performed 8 months after the patient’s discharge from the hospital confirmed resolution of the necrosis and revealed no evidence of strictures (Panel B).