BACKGROUND: Barrett's esophagus (BE) is a condition in which the normal squamous epithelium is replaced by abnormal columnar mucosa with intestinal metaplasia, secondary to a long-standing gastroesophageal reflux. Although there are several experimental evidences in respect to this abnormal development, no clinical data has been published before concerning the appearance of abnormal intestinal metaplasia in human subjects. METHODS: In this report we reviewed 3 different clinical studies in which our group has shown the development of BE in patients in whom no BE was present before surgery. RESULTS: Three different esophagogastric operations have been evaluated which produce gastroesophageal reflux either by resection of the lower esophageal sphincter, or by the increasing of duodeno-esophageal reflux by gastrointestinal anastomosis or after antireflux surgery. After any of these operations, the development of intestinal metaplasia of the distal esophagus and esophagogastric junction takes time, at least 90 months after surgery. CONCLUSIONS: Therefore, in order to demonstrate the appearance of BE after surgery, it is necessary a) to follow up for a longterm (10 years or more) and b) to perform several consecutive endoscopic and histological evaluations.