Objective To compare the structural diversity of H.pylori CagA protein C-terminal and biological activities of H.pylori on gastric epithelial cells.Methods The CagA gene 3′terminal variable region was amplified with PCR.The PCR products were sequenced.AGS cells were cocultured with H.pylori strains.Cells were examined for cellular elongation by light microscopy.IL-8 production in cell supernatant was measured by ELISA.Results The amino acid sequences surrounded the third EPIYA site varied among different ethnic strains.Cag PAI+H.pylori strains from different ethnic groups showed no different ability of inducing IL-8 production and cellular elongation.Cag PAI+H.pylori strains showed higher level ability of inducing IL-8 production and cellular elongation than Cag PAI-H.pylori strains.Conclusion The amino acid sequences of cagA gene 3′terminal variable region varied among different ethnic strains.Ability of H.pylori inducing IL-8 production and cellular elongation may depend on cag PAI.