Human lactoferrin (hLF) is a glycoprotein containing 692 amino acids and found in the saliva, milk, tears, and other body fluids. Peptide representing the first cationic domain, i.e. a peptide comprising the first eleven residues of hLF (further referred to as hLF1-11) was significantly more effective than the full length hLF or the peptide representing the second cationic domain in killing a variety of bacteria in vivo. The mechanism of action comprises a number of independent factors. The classical way to explain the efficacy is the direct killing effect, which typically is observed in vitro at relatively high concentrations. The results of in vitro and in vivo experiments suggest that the mechanism of action is predominantly through the intermediary of cells and/or components of the host as opposed to a direct interaction with the pathogen.