Very few epidemiologic data on reflux oesophagitis are available. To estimate the incidence of reflux oesophagitis, all reports (n = 6733) of upper gastrointestinal endoscopy performed in patients aged > or = 16 years and living in a defined catchment area of 226,776 inhabitants were examined during a 2-year period. The incidence of reflux oesophagitis was calculated to be 120 per 100,000 inhabitants, and most of the incident cases (88%) were uncomplicated oesophagitis with single or multiple erosions. The incidence of complicated oesophagitis and Barrett's esophagus was 5.6 and 1.7 per 100,000, respectively. The mean age of all incident subjects was 56 +/- 18 years (range, 17-88 years) with a male to female ratio of 2:1. The severity of oesophagitis increased significantly with age (p = 0.0003), and most (75%) of the patients with complicated oesophagitis were > or = 60 years of age. Men had more severe grades of oesophagitis than women (p = 0.0003), and endoscopic evidence of peptic ulcer disease was observed in one of five patients.