Spontaneous intramural dissection of the esophagus (SIDE) is an unusual clinical entity. It is a benign disease that, despite its alarming endoscopic appearance, usually responds well to conservative management and has an excellent prognosis. Nevertheless, some situations require emergency surgical treatment. These situations include esophageal perforation with mediastinitis, massive bleeding, and abscess, among others. Upper gastrointestinal endoscopy is a useful diagnostic test when radiological examinations (hydrosoluble contrast esophagogram, computed tomography, or magnetic resonance imaging) have excluded perforation. We present the case of a 42-year-old woman who was admitted to our hospital complaining of acute chest pain, dysphagia, and odynophagia. Because of the persistence of symptoms and diagnostic uncertainty (SIDE versus complicated esophageal duplication cyst) surgery was performed. The definitive diagnosis was SIDE.