Background:The evidence that some strains of Lactobacillus and Bifidobacteriumare able to inhibit H.pylori growth through the release of bacteriocinsor organic acids. Therefore, it is important to in vitro study develop low-cost, large-scale, alternative probiotic to the at-risk population to prevent or decrease H. pyloricolonization.Methods:18 samples of gastric biopsies were cultured according to standard microbiological proceduresand were grown under microaerophilic conditions on selective Pylori agar. An in vitro disk diffusion assay was employed to assess the lactic acid bacteria LBO1, 2, 3, 4, 6, 7 cells and cell free supernatants (CFS) and bifidobacteria BFO1, BFO4 anti-H.pylori activity.Results: Ability of LBO1 strain to inhibit growth of H.pylori is 55,5% [95% CI 32.5-78.4], LBO-2 88,8% [95% CI 74.2-103.3], LBO-3 50%[95% CI 26.9-73.0]and LBO-4 38,8% [95% CI 32.5-78.4]. Then LBO 6 and LBO7 strains had no inhibitory activity against H.pylori. Average inhibition zone is 8-14mm (11,6 mm) for LBO1 strain, 10-16mm (11.3mm) for LBO2 strain , 8-12mm (10,2mm) for LBO3 strain and 10-12mm (10,5mm) for LBO4 strain.Inhibitioryactivity of Lactobacillus LBO1 supernatant against H.pylori accounts for 61.1% (n=11), LBO2 supernatant for 72,2% (n=13), and LBO3 supernatant for 33,3% (n=6) , while LBO4 supernatant inhibits only HP78 strain. LBO6 and LBO7 supernatants were both Lactobacillus LBO cultures. Average inhibition zone is 8-12mm (10 mm) for LBO1 supernatant, 10-16mm (11.3mm) for LBO2 supernatant , and 10-12mm (10,3 mm) for LBO3 supernatant.Bifidobacterium BFO1 strain was 83.3% inhibition activity. But BFO4 was not inhibit against all H.pylori strains.Conclusion:Lactobacillus LBO2 and Bifidobacterium BFO1 strains were isolatedfrom Mongoliantraditional fermented milk product were obtained more inhibition against H.pylori strains other LactobacillusLBO and Bifidobacterium BFO strains.