Naturally occurring cationic host defence peptides, also known as antimicrobial peptides, can control infections by their direct microbicidal properties and by modulating the host’s immune responses. In addition, certain cationic host defence peptides can resolve harmful inflammation. Here, Mookherjee et al. assess the emerging potential to therapeutically harness these peptides to treat infectious diseases, chronic inflammatory disorders and wound healing, highlighting current preclinical studies and clinical trials.