Abstract: In this study, the ability of two antibiotics daptomycin and pantoyl lactone to inhibit growth of horse originated pathogen Streptococcus equi by disrupting plasma membrane of the bacterium was investigated using agar diffusion and micro tube dilution methods. The results obtained from this study indicated that daptomycin was more effective in inhibiting the growth of the pathogen in vitro than the second antibiotics. The 3 tested strains were susceptible to daptomycin but completely resistant to pantoyl lactone. Hence, daptomycin therefore tends to be potent for treating horse infections caused by this pathogen.