Abstract:To study the pathogenetic role of Helicobacter pylori, colonization of this organism was attempted in conventional rhesus monkeys. After inoculation of human H. pylori to the gastric mucosa of four 10‐year‐old monkeys, endoscopical and histological examinations were repeated for 10 weeks. The organisms were recovered bacteriologically from all 4 monkeys at the first week, from 3 animals at the 2nd, and from 2 animals at the 6th to 10th week. The endoscopical examination showed only minimum changes in the mucosal appearance such as erythema and erosion due to H. pylori colonization throughout the study. In contrast, the histological examination revealed prominent polymorphonuclear cell infiltration, edema of the mucosa and dissected epithelium at the earlier periods and mononuclear cell infiltration afterwards. The maximum lymphocyte reaction such as clusters or the formation of a thick layer at the bottom of the lamina propria was observed at the 8th week. These results indicated that rhesus monkeys can be infected by human H. pylori resulting in similar pathologic changes in the human stomach, and that this animal model may be useful for future stud