OBJECTIVE:Helicobacter pylori (H. pylori) is a gram-negative bacterium and one of the reasons for gastritis, peptic and duodenal ulcers. It is a crucial public health problem for both children and adults, especially in developing countries. This study aims to investigate the prevalence of Helicobacter pylori positivity in children and to compare with updated Sydney classification criteria. METHODS:This study was conducted from January 2015 to June 2017. This study included 885 children aged 0-17 year(s). Endoscopic biopsies were evaluated for the diagnosis of infection due to H. pylori. RESULTS:The findings showed that 418 (47.2%) of 885 children were positive for H. pylori, and this positivity had a significantly increasing correlation with the presence of chronic inflammation, neutrophilic activity, lymphoid aggregates, and follicles. Erythematous pangastritis and antral nodularity on endoscopic findings had a correlation with H. pylori positivity. CONCLUSION:In this hospital-based study, the findings suggest that H. pylori infection is a problem for children and more extensive studies are needed to determine the prevalence of H. pylori positivity among children.