Native peptides exhibit various biological activities from which the antimicrobial property is one of the most frequently studied. A convenient way of telling whether peptides influence the life cycle of bacteria is the broth microdilution assay. In this measure, growing bacteria are incubated with peptides and growth inhibition is detected with colorimetric methods. Highly charged and protease-sensitive peptides need special considerations in assay design and readout interpretation to reveal the true antimicrobial efficacy and potential utility as human or veterinary therapeutics. The broth microdilution assay is suitable for first assessment of antimicrobial resistance induction.