In 98 patients with chronic gastritis clinical-morphologic analysis was performed. The analysis included: the examination of gastric biopsy specimens, determination of HP-status by means of a group of methods, determination of antibodies to H+/K+ -ATPase of parietal cells of the gastric wall, IgG-EA-EBV and IgM-NA-EBN antibodies in the blood serum by means of IFA method, pepsinogene I, pepsinogene II, gastrin and antibodies to Hp with the use of Biohit gastric panel, 24-hour monitoring of intragastric pH with the use of Gastroscan-24 machine. Comparison of all parameters was performed in 4 groups: 27 children aged 6-17 with non-autoimmune gastritis and 119 children with gastritis of other etiology, 34 patients aged 18-80 with autoimmune gastritis and 43 patients of the same age group with non-autoimmune gastritis were described. Age-specific peculiarities of autoimmune gastritis in children were determined; and a diagnostic algorithm for its early diagnosis in the latter was developed.