The invention relates to polypeptides, comprising repeats of peptides derived from apolipoproteins, which exhibit antibacterial activity and to nucleic acids encoding the same. The invention further provides the use of such polypeptides, derivatives, analogues or nucleic acids as medicaments, and also their use in methods of preventing or treating bacterial infection or objects and surfaces. The invention further extends to objects, such as contact lenses, coated with the polypeptides.