Four patients were found with patches of gastric fundal type epithelium just distal to the cricopharyngeus, separated from the gastroesophageal junction by 15-20 cm of normal squamous epithelium. Three of the four had symptoms of dysphagia localized to the area of the esophagus containing the epithelium. Congo red dye (a pH indicator) applied to the mucosa during endoscopy revealed acid production by the mucosa after stimulation with pentagastrin. Interestingly, the patients' symptoms decreased during treatment with cimetidine only to return on cessation of therapy.