Abstract: Objective To study the role of helicobacter pylori(Hp) infection and mutation of p53 and ras in development of gastric cancer. Methods Mutation of p53(exon 7) and ras(codon 12) was analyzed by PCR-SSCP.Hp infection was detected by rapid urease test(RUT) with hematoxylin-eosin staining. Results The positive mutation rate of p53 and ras was 67.47% and 63.86%,respectively,in 83 gastric cancer tissue samples.No significant difference was found between males and females.The positive mutation rate of p53 and ras was higher in patients with distant metastasis than in those with no metastasis.No mutation of p53 and ras was observed in control group.The Hp infection rate in gastric cancer tissue was 71.08%,which was significantly higher than that in normal tissue(P<0.01).The mutation rate of p53 and ras was significantly higher in positive Hp infection tissue than in negative Hp infection tissue(P<0.05). Conclusion Hp infection and mutation of p53 and ras may play a role in development of gastric cancer.Hp infection can lead to mutation of multiple genes.PCR-SSCP in combination with detection of mutation of p53 and ras contributes to diagnosis of gastric cancer and prediction of its distant metastasis.