Gastroesophageal reflux disease is the most common gastrointestinal diagnosis recorded during visits to outpatient clinics. The spectrum of injury includes esophagitis, stricture, the development of columnar metaplasia in place of the normal squamous epithelium (Barrett's esophagus), and adenocarcinoma. Barrett's esophagus is a premalignant lesion detected in the majority of patients with esophageal and gastroesophageal adenocarcinoma. The incidence of these cancers has been increasing in the United States and they are associated with a low rate of survival (5-year survival rate, 15-20%). When symptoms of gastroesophageal reflux disease are typical and the patient responds to therapy, no diagnostic tests are necessary to verify the diagnosis. Endoscopy is the primary test in patients whose condition is resistant to empirical therapy but its yield in this setting is low because of the poor correlation between symptoms attributed to the condition and endoscopic features of the disease. Clinical experience suggests that lifestyle modifications may be beneficial for gastroesophageal reflux disease although trials of the clinical efficacy of dietary or behavioral changes are lacking. Abundant data from randomized trials show benefits of inhibiting gastric acid secretion and suggest that proton-pump inhibitors are superior to H2-blockers and that both are superior to placebo. In patients with Barrett's esophagus, antireflux interventions are intended to control symptoms of reflux and promote healing of the esophageal mucosa. If a patient has symptoms refractory to proton-pump inhibitors or cannot tolerate such therapy, antireflux surgery, most commonly Nissen fundoplication, may be an alternative management approach. In patients with high-grade dysplasia, endoscopic therapies or surgical resection must be considered.