Barrett's oesophagus is defined as the occurrence of columnar epithelium extending for more than 3 cm up into the tubular part of the oesophagus. The average age at the time of diagnosis is 55 years. The condition is most often seen in men and is rare among negroid populations. The condition is caused by a combination of pronounced gastro-oesophageal reflux, hypersecretion of acid by the stomach, motoric and sensory dysfunction in the oesophagus, as well as increased aggressiveness of the refluxed material. The diagnosis is made by endoscopy, taking biopsies. Three types of histological epithelium occur: specialized columnar epithelium, junctional-type epithelium and gastric fundus-type epithelium. Barrett's oesophagus is a premalignant condition. Severe dysplasia is correlated with the development of oesophageal adenocarcinoma. The incidence of the latter varies between 1:441 and 1:52 per patient-year. The treatment of Barrett's oesophagus is either medical treatment or surgery. The medical treatment includes H2 receptor antagonists or omeprazole. Antireflux surgery is indicated in cases resistant to medical treatment. Resection is the only possible curative treatment when severe dysplasia or adenocarcinoma is present. Recommendations are made, based on the available literature, as to the treatment and follow-up of patients with Barrett's oesophagus.