One of the newest conceptions on the causes of gastritis, duodenitis, peptic and duodenal ulcers states that an infectious factor--Helicobacter pylori is responsible. The purpose of the this study was to estimate the frequency of Helicobacter pylori among children and the correlation between its presence and gastritis, duodenitis, peptic and duodenal ulcers and biliary reflux. Helicobacter pylori infection seems to be a serious etiopathogenic factor of stomach and duodenal diseases among children. Inflammatory changes of the gastric mucosa, as well as peptic and duodenal ulcers more frequent in children with H. pylori.