The normal white appearance of the esophageal epithelium is replaced by irregular red areas that microscopically display columnar metaplasia with scattered goblet cells. This is Barrett esophagus, a complication of long-standing gastroesophageal reflux disease (GERD). Patients with Barrett esophagus usually have more severe reflux disease with significant impairment of lower esophageal sphincter function and esophageal body motility compared with patients without Barrett esophagus. Patients often have a history of pronounced reflux symptoms such as heartburn. Barrett esophagus can be complicated by ulceration with bleeding and stricture. A more feared complication is the development of epithelial dysplasia that can progress to adenocarcinoma. The diagnosis of Barrett esophagus can be made by endoscopy with biopsy, and patients can receive follow-up for surveillance to determine the development of dysplastic changes.