Abstract: Objective To detemine the mle of Helicobacter pylori(HP) in the development of gastric cancer and gastric precancemus lesions. Methods the point mutation of C-Ha-Ras gene was detected by polymerase chain reaction-single strand conformation polymorphism analysis-direct sequence(PCR-SSCP-Sequence ) Results the mutational rates of C-Ha-Ras gene in Hp positive patients were significantly higher than those in Hp negative patients.For gastric cancer patients, the mutational rate of P53 gene in Hp positive patients were significantly higher than those of Hp negative patients. Conclusion Hp infection may be in relation with gastrocar- cinogenesis, the gene mutation may play a role in Hp related gastric cancer.