Barrett's oesophagus is a premalignant metaplastic change of the oesophageal mucosa. Due to its relationship with oesophageal reflux disease and the development of adenoma-carcinoma of the oesophagus the problem arouses increasing interest. In the wide pathogenesis of the disease most probably the composite effect of the refluxed HCl content and duodenal juices play a part. In the diagnosis in addition to fundamental methods--endoscopy and histology--increasingly chromoendoscopy and fluorescent endoscopy are involved. Dispensarization of patients is essential and depends on the degree of pathohistological epithelial changes. Treatment of Barrett's oesophagus can be divided into conservative, where the drug of choice are proton pump inhibitors, and surgical treatment. Promising is endoscopic ablation of the epithelium in combination with subsequent antisecretory therapy.