Introduction and Objective: The genus Bifidobacterium can generally be found in quantity in the habitats such as human and animal gastrointestinal tract, dental caries, vagina and oral cavity. The aim of this study was to isolate Bifidobacterium from stool and determine their inhibitory effect against some pathogens. Materials and Methods: 130 samples were collected by wet swabs and kept in sterile tubes containing MRS broth media. And Bifidobacterium isolated from stool was enriched in Man-Rogosa-Sharpe medium (MRS) broth and isolated by growing on MRS agar medium and characterized by phenotypic characteristics and PCR technique at genus and species levels. The antimicrobial substance was extracted from ethyl acetate solvent and the antimicrobial activity against some pathogenic bacteria, such as Salmonella typhi and Shigella sonnei, were investigated. Results: Eleven Bifidobacterium bifidum and four Bifidobacterium adolescentis, which were isolated from fresh stool, were identified by PCR. Antimicrobial substance from MRS broth medium was extracted. This antimicrobial compound showed a potent inhibitory activity against four tested bacteria. These bacteria produced acetic acid and lactic acid as inhibitory substances that were different from bacteriocins. Conclusion: Fresh stool may be used as a source of antimicrobial lactic acids bacteria, Bifidobacterium bifidum and adolescentis as two probiotics can establish themselves in gut and urogenital tract to prevent the human body from adverse effects of pathogens.