In a prospective endoscopic and bioptic study, 141 control subjects and 359 patients with symptoms of gastroesophageal reflux (GER) were included to determine the prevalence of cardial epithelium inflammation or 'carditis' and to determine the prevalence of Helicobacter pylori in this area. Two biopsies at the antrum, four distal to the squamous-columnar junction and two proximal in the esophageal mucosa, were taken. Patients with gastroesophageal reflux were divided into four groups, according to the severity of endoscopic findings: patients without esophagitis, patients with erosive esophagitis, patients with short-segment and long-segment Barrett's esophagus (BE). Control subjects had normal histological findings at the cardia in 90% of cases, fundic mucosa being present twice as cardial epithelium. Carditis was present in 8% of cases and intestinal metaplasia (IM) in 2%. On the contrary, patients with GER had carditis in nearly 50% of cases. Intestinal metaplasia was present in 12% of cases with GER without esophagitis or erosive esophagitis, in 35% of cases with short-segment BE and in 65% of the cases with long-segment BE. IM at the antrum was present in only 5% of cases. Helicobacter pylori at the squamous-columnar junction was present in 13% of control subjects and in 30% of the patients with GER. It is concluded that carditis is an easy and objective marker for the presence of chronic gastroesophageal reflux and the presence of Helicobacter pylori at this region must be carefully evaluated in order to determine some pathogenic role for the development of Barrett's esophagus.