Objective    To evaluate the role of mitochondrial pathway in apoptosis of gastric cancer cell line SGC-7901 induced by Helicobacter pylori(H. pylori).     Methods    Apoptosis was evaluated in SGC-7901 cells by flow cytometry. RT-PCR and Western blotting were used to measure the expressions of genes and proteins associated with mitochondrial pathway. Effect of caspase inhibitors on apoptosis induced by H. pylori strain NCTC11637 was investigated.     Results    NCTC11637 directly induced apoptosis in SGC-7901 cells. Apoptotic rate was 6.30%

11.57%

8.63% and 7.22% respectively at 6

12

24 and 48 h after coculture with H. pylori.  H. pylori upregulated the expression of Bax

and induced a time-dependent activation of caspase-9 and -3. Apoptosis was inhibited significantly by pre-incubation with the inhibitors of caspase-9 and -3. Caspase-8 inhibitor reduced H. pylori-induced apoptosis by 20%.      Conclusion    H. pylori infection upregulates the expressions of Bax mRNA and protein in gastric cancer cell line SGC-7901

and induces activation of caspase-9 and -3. Mitochondrial pathway may be the major one in H. pylori-induced apoptosis in SGC-7901.