Abstract: The present invention relates to a biocidal fusion peptide comprising: a) a peptide LL-37 or an active fragment or active derivative thereof; b) and a further heterologous bioactive peptide or an active fragment thereof, wherein part or all of the amino acid sequence of the fusion peptide is predicted to form an alpha-helix structure for disruption of a pathogen membrane, compositions such as pharmaceutical compositions comprising the same, methods of preparing the peptide and use of the peptides in treatment, in particular for the treatment of bacterial infection and/or fungal infection and/or viral infection.