Objective: To investigate the inter-relationship between the cagA gene of Helicobacter pylori and the gastric mucosal damage

the gastric cell proliferation. Methods: The cytotoxin-associated gene (cagA) was detected by polymerase chain reaction in fifty patients infected with Helicobacter pylori. We investigated the degree of the gastric mucosal inflammation

the prevalence of intestinal metaplasia

lymphoid follicles

atrophy and the gastric cell proliferation activity of all these patients. Results: Thirty-seven of the patients were cagA positive and thirteen of them were cagA negative.The positive rate of cagA gene in peptic ulcer patients was higher than that in chronic gastritis patients(P <0.01). Individuals with cagA+ strains had significantly higher degree of gastric mucosal inflammation and gastric mucosal proliferation cell nuclear antigen labeling indices (PCNA LI)than persons infected with cagA- strains(P <0.05).There were no significant differences in the prevalence of intestinal metaplasia

lymphoid follicles and atrophy(P >0.05). Conclusion: The cagA gene is one of the toxic items of Helicobacter pylori

but not the only element leading to the gastrointestinal disease.