Helicobacter pylori attaches via lectins, carbohydrate binding proteins, to the carbohydrate residues of gastric mucins. Guinea-pigs are a suitable model for a H. pylori infection and thus the carbohydrate composition of normal and H. pylori infected gastric mucosa was investigated by lectin histochemistry. The stomach of all infected animals showed signs of an active chronic gastritis in their mucosa, whereas no inflammation was present in the control animals. The corpus-fundus regions of the controls showed heterogeneous WGA, SNA-I, UEA-I and HPA binding in almost all parts of the gastric glands. While these lectins labelled the superficial mucous cells and chief cells heterogeneously, the staining of the parietal cells was limited to WGA and PHA-L. Mucous neck cells reacted heterogeneously with UEA-I, HPA, WGA and PHA-L. In the antrum, the superficial mucous cells and glands were stained by WGA, UEA-I, HPA, SNA-I or PHA-L. WGA, UEA-I, SNA-I and HPA labelled the surface lining cells strongly. The mucoid glands reacted heterogeneously with WGA, UEA-I, HPA, SNA-I and PHA-L. In both regions, the H. pylori infected animals showed similar lectin binding pattern as the controls. No significant differences in the lectin binding pattern and thus in the carbohydrate composition between normal and H. pylori infected mucosa could be detected, hence H. pylori does not induce any changes in the glycosylation of the mucosa of the guinea-pig. This unaltered glycosylation is of particular relevance for the sialic acid binding lectin SNA-I as H. pylori uses sialic acid binding adhesin for its attachment to the mucosa. As sialic acid binding sites are already expressed in the normal mucosa H. pylori can immediately attach via its sialic acid binding adhesin to the mucosa making the guinea-pig particularly useful as a model organism.