Lactoferrin is a member of the transferrin family of iron-binding proteins. Numerous functions have been reported and continue to be reported for the protein, some of which are related to its iron-binding properties. Its extensive antimicrobial activities were originally attributed to its ability to sequester essential iron, however, it is now established that it possesses bactericidal activities as a result of a direct interaction between the protein or lactoferrin-derived peptides. This article reviews the antimicrobial activities of lactoferrin and discusses the potential mode of action of lactoferrin-derived cationic peptides against Gram-negative bacteria in the light of recent studies.