Twenty bifidobacterial strains were tested for adherence ability with cellular model systems in vitro. Strain A03 and I06 showed high adherence to the epithelial cells. The inhibitory effects of Strain A03 and I06 on enteropathogen Staphylococcus aureus and Escherichia coli were demonstrated by simultaneous incubation and antimicrobial testing. These antibacterial activities were mainly induced by organic acids produced by bifidobacteria. The release of LDH of Caco-2 cells which were differently treated with bifidobacteria and enteropathogen, suggested that the adherence of bifidobacteria were essentially different with those of enteropathogen, and the adhesion of strain A03 and I06 could prevent the harmful effect of S. aureus and E. coli on Caco-2 cells.