The natural history of metaplasia and dysplasia in Barrett esophagus is not well defined. Publication bias, the selective reporting of studies that have positive or extreme results, has exaggerated the risk of esophageal adenocarcinoma in this condition. Recent data suggest that patients with Barrett esophagus develop these tumors at the rate of 0.5% per year, a cancer incidence considerably lower than was appreciated just a few years ago. Indirect evidence suggests that aggressive treatment of gastroesophageal reflux might decrease the risk of carcinogenesis, but no therapy yet has been proved to decrease the incidence of cancer in Barrett esophagus. Dysplasia in the metaplastic epithelium clearly is a worrisome finding, but the progression from dysplasia to cancer may take years and may not be inevitable.