Gastroscopy with biopsies was performed in 178 children with upper abdominal pain. Of them 109 (61%) had gastritis and 104 (58%) Helicobacter pylori (HP) in antrum and/or corpus. Gastritis consisted in most cases (87% of antral and 86% of corpus gastritis) of mild superficial round cell infiltration. Mucosal atrophy was not found. Accumulation of granulocytes was present in 43 patients and lymphonoduli were found in 33 patients, usually in connection with gastritis. Gastritis affected only the antrum in 18%, only the corpus in 5% and both antrum and corpus in 62% of the cases of gastritis. There was a good correlation between morphology and bacteriology in the antrum and a satisfactory one in the corpus. However, in some cases gastritis was present without bacteria and in some cases a normal mucosa was associated with bacteria. Gastritis and HP prevalences showed a general increasing trend with age, but significances were with one exception lacking. It is tentatively concluded that gastritis begins in childhood as a slight and chronic superficial infiltration affecting usually antrum and corpus simultaneously. In the majority of cases gastritis is associated with HP infection, which seems to start the process. It is possible that the HP-related gastritis is a common cause of abdominal complaints in children; however, convincing evidence is lacking.