The objective of the present study is to investigate the interaction between PAMAM dendrimers and solid supported model biomembranes of high fluidity. These membranes consist of bilayers floating over a significant water layer, which should be compared to previous neutron reflectometry experiments where the model membranes applied have been single bilayers prepared by the deposition from mixed micellar solutions as well as small unilamellar vesicles. In our recent studies, dendrimers have been shown to penetrate model membranes, which supports the transfecting ability proposed for PAMAM dendrimers. In this study however, the membranes applied will be retaining the fluidity of real cell walls and will therefore serve as better models for cell membranes. The information gained will give new insight into the transfection mechanism using non-viral gene carriers.