Abstract: In this research, we have aimed to determine antagonistic effects of various lactic acid bacteria against Gram (+) and Gram (-) bacteria with a comparison of disc diffusion and spot-on-lawn method. In spot-on-lawn method, P. aeruginosa ATCC 27853 was the most sensitive of the tested bacteria, followed by E. coli ATCC 25927 and P. aeruginosa ATCC 10145. On the other hand, in disc diffusion assay B. subtilis ATCC 6633, E. coli O157:H7 and P. aeruginosa ATCC 10145 were the most sensitive indicator microorganisms. The spot-on-lawn method was suitable for assessing the antagonistic effect of lactic acid bacteria. In general, inoculum density had little effect on inhibition.