We have investigated the role of Helicobacter pylori infection and of other risk factors of gastritis and carditis in residents of a high-risk area for gastric cardia cancer. During a national population-based endoscopic survey, 508 randomly-selected participants aged > or =40 were enrolled. Mucosal biopsies were obtained from six standard sites. Polymorphonuclear (PMN) and mononuclear (MN) infiltration and combined inflammatory scores (CIS) for chronic gastritis and H.pylori were assessed. Relationships of H.pylori and reflux esophagitis with these variables were calculated for cardia and non-cardia subsites. Both PMN and MN infiltrations correlated strongly with H.pylori infection. For PMN the relationship was maximum for the antrum (odds ratio (OR) = 9.4 (5.2-17.1)) and minimum for the gastric body (OR = 1.7 (1.0-2.9)). There was a significant relationship between carditis and H.pylori (OR = 2.8 (1.7-4.9)). A similar relationship was obtained for MN infiltration. In 56% of subjects the mean MN score for the corpus was equal to or greater than that for the antrum. For 59% of subjects the MN score for the cardia was greater than or equal to the antral score. Use of logistic regression revealed that was the main risk factor for gastritis and carditis in all sites. There was an inverse relationship between reflux esophagitis and carditis. H.pylori is the main risk factor for gastritis for all sites of the stomach including the cardia; but this relationship is stronger for the antrum and cardia than for the body. Continuous cardia inflammation may contribute to the high incidence of gastric cardia cancer in this region.