The authors review the literature about the assessment of risks of adenocarcinoma occurring over the natural history of Barrett's oesophagus with an incidence much higher than in the general population. The best marker is histological analysis of the cylindric epithelium for signs of dysplasia or early carcinoma. Although there is much controversy about the practical benefit of regular surveillance, the authors recommend a yearly endoscopy with multiple site biopsies. With the new potent drugs aimed at controlling gastro-oesophageal reflux, regression of metaplasia might occur, as the authors have observed in 3 patients treated by 60 mg omeprazole. However, prospective studies are needed to confirm this finding and its possible effect on reducing the risk of adenocarcinoma.