A previous study reported a relationship between the expression of heat-shock protein 60 (HSP60) by Helicobacter pylori and its adhesion to human gastric carcinoma (MKN45) cells. To examine whether the HSP60 homologue of H. pylori is associated with the adhesion of H. pylori to human gastric epithelial cells, an inhibition assay of adhesion of H. pylori to MKN45 cells was performed by flow cytometric analysis with monoclonal antibody (MAb) designated as H20 recognising HSP60 of H. pylori. The rate of adhesion of H. pylori pretreated with MAbH20 to MKN45 cells was lower than that of untreated H. pylori. Primary human gastric epithelial cells from a patient with gastric cancer were also prepared for comparison in the inhibition assay with MAbH20. H. pylori adhered to the primary human gastric epithelial cells, and this adhesion was significantly inhibited by MAbH20. These results suggest that the H. pylori HSP60 homologue recognised by MAbH20 might be associated with the adhesion of H. pylori to primary human gastric epithelial cells as well as to cultured gastric cancer cells.