This study tested whether there were different expressions of gastric Lewis antigens between children and adults with Helicobacter pylori infection, and whether the difference was related to the infection outcome. About 68 dyspeptic children and 110 dyspeptic adults were enrolled to check H. pylori infection, its colonization density, and the related histology. Gastric Lewis antigens b (Le(b)), x (Le(x)), and sialyl-Lewis x (sialyl-Le(x)) were immunohistochemically stained and scored for the intensity. The H. pylori-infected adults, but not the children, had a lower Le(b) intensity over the antrum (p=0.019) but higher Le(b) intensity over the corpus (p=0.001) than the non-infected ones. Over the antrum, both the H. pylori-infected children and adults had a lower Le(x) and higher sialyl-Le(x) intensity than those non-infected ones (p<0.05). The H. pylori-infected adults had a higher bacterial density (p=0.004) and Le(b) intensity (p=0.016) over the corpus than the H. pylori-infected children. For the H. pylori-infected adults, but not children, the corpus had a higher Le(b) (p=0.038) and lower Le(x) (p=0.005) intensity than the antrum. Furthermore, the H. pylori-infected adults expressed a higher Le(b) and had a higher bacterial density than those with weak Le(b) (antrum, p<0.001; corpus, p=0.001). In conclusion, H. pylori infection is associated with the intensity change of Lewis antigen expressions in the stomach. The changes of gastric Lewis antigen expressions are different between adults and children with H. pylori infection, which may exert different H. pylori colonization over the corpus between adults and children.