The present invention provides antimicrobial peptides. The peptides are non-glycosylated, less than about 100 amino acids in length, and include an amino acid sequence selected from: AVESTVATLEAΣPEVIESPPE (SEQ ID NO:3), AVESTVATLEDΣPEVIESPPE (SEQ ID NO:4), AVESTVATLEASPEVIESPPE (SEQ ID NO:5), AVESTVATLEDSPEVIESPPE (SEQ ID NO:6), DMPIQAFLLYQQPVLGPVR (SEQ ID NO:7), and conservative substitutions therein. These peptides can be produced synthetically; however, they can most conveniently be derived from casein.