Purothionins and defensins are basic, amphiphilic, cysteine-rich and low molecular weight plant defence proteins. These proteins are active against a broad range of phytopathogenic fungi, andcan be potentially exploited both in terms of environmentally friendly plant fungicides and as future human therapeutic agents. The aim of our research is to investigate the mode of binding of these proteins to model fungal lipid bilayers. We propose to carry out neutron reflectivity experiments at the solid/liquid interface to investigate the influence of membrane unsaturation and the presence of sterols on protein binding, as well as kinetics of protein adsorption. The findings from the NR studies will determine quantitatively the protein-lipid interfacial layer structure and will enable the differences in the proteins' mode of action at membrane surfaces to be investigated.