Antimicrobial peptides (AMPs), also called host defense peptides, are part of the innate immune system of essentially all species, from bacteria themselves to mammals to protect against bacterial pathogens. Although the exact microscopic mechanism(s) is still debated, this chemical structure allows them to target bacterial cell membranes which have net negative charge, selectively. One hypotheses of the mode of action is that AMPs interacts with cardiolipins (CL), and important anionic lipid present in bacterial membranes where its function is essential for bacterial pathogenesis and survival in various environments. In this project we set out to investigate whether the distribution of CL is disturbed by AMPs using neutron reflectometry. The obtained results will guide ongoing strategies in designing new effective peptide based antibiotics against resistant bacterial strains.