From The New England Journal of Medicine Barrett's esophagus, a medical curiosity since its initial description in the early 1950s, has emerged as an intensively studied condition. Several factors might explain this transformation. First, Barrett's esophagus is one of the most easily studied examples of human carcinogenesis, within reach of an endoscope (and biopsy), and can be studied in some patients over a period during which the sequence of events from injury to dysplasia to cancer occurs. Second, it is common in the Western world, present in about 10 percent of patients with gastroesophageal reflux disease who undergo endoscopy and perhaps 1 percent of the general population, thus lending itself to epidemiologic study. Third, it is on the spectrum of gastroesophageal reflux disease treated by the most commonly used drugs in the pharmaceutical industry and is amenable to a wide range of innovative endoscopic and surgical techniques. Fourth, and most compellingly, news of the association of gastroesophageal reflux disease with esophageal adenocarcinoma has reached the lay public, greatly raising awareness of and interest in this disorder.