Three common foodborne pathogenic bacteria, Staphylococcus aureus, Escherichia coli and Shigella flexneri, were selected for assessing the antibacterial activity of L- and D-lactic acid as indicated by minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The growth of all these foodborne pathogens was inhibited in the presence of L- or D-lactic acid. Both showed an MIC of 0.1 mg/mL for all the pathogens and an MBC of 3.2, 1.6 and 3.2 mg/mL for Staphylococcus aureus, Escherichia coli and Shigella flexneri, respectively. L-lactic acid more significantly inhibited the three indicator strains at a density of 105–106 CFU/mL than its D-isomer when present at a concentration of 0.2 mg/mL.