Acute esophageal necrosis or black esophagus is a rare condition, reported for the first time in 1990. This disease is defined as a diffuse blackened aspect of the esophagus observed by upper gastrointestinal endoscopy associated with the histopathological findings of necrosis of the esophageal mucosa. It is always noted in severely compromised patients. The diagnosis is possible using endoscopy. Its cause remains unknown but is probably multifactorial. An esophageal ischemic injury should be considered. It is important that a differential diagnosis is made with consideration of other necrotic conditions of the esophagus. Only supportive treatment and the improvement of the associated disease appear possible. In the present case report we describe the clinical, endoscopic and histopathological characteristics of black esophagus observed in three patients and present a review of the literature.