AIM: To study the effects of different Helicobacter pylori (H py/orl) culture filtrates on growth of gastric epithelial cells.METHODS: Broth culture filtrates of H pylori were prepared. Gastric epithelial cells were treated with the filtrates, and cell growth was determined by growth curve and flow cytometry. DNA damage of gastric epithelial cells was measured by single-cell microgel electrophoresis.RESULTS: Gastric epithelial cells proliferated actively when treated by CagA-gene-positive broth culture filtrates, and colony formation reached 40%. The number of cells in S phase increased compared to controls. Comet assay showed 41.2% comet cells in GES-1 cells treated with CagA-positive filtrates (P<0.05).CONCLUSION: CagA-positive filtrates enhance the changes in morphology and growth characteristics of human gastric epithelial tumor cells. DNA damage maybe one of the mechanisms involved in the growth changes.