Using strict criteria for diagnosis, 23 patients having benign Barrett's esophagus, and 20 patients with adenocarcinoma arising in this epithelium have been analyzed. Evidence supports severe gastroesophageal reflux as a cause of Barrett's esophagus. Successful antireflux surgery leads to stabilization and possibly regression of the dysplasia in Barrett's epithelium, and can be followed by squamous epithelial regeneration in some. Antireflux surgery is advocated in all patients with Barrett's esophagus demonstrated to have abnormal reflux regardless of symptoms. The malignant potential of the columnar epithelium is higher in men who smoke, in patients with intestinal-type metaplasia who continue to have severe reflux, and in patients who develop dysplasia. In those with high grade dysplasia, the probability of carcinoma is high and esophagectomy should be seriously considered in the hopes that the pathological stage of the neoplasm is still favorable.