In this paper the general requirements for a passenger-car side door made of FRP are presented as well as a description of different concepts for self supporting monocoque FRP-doors. For one conceptual design static and dynamic analyses have been made to investigate more detailed the potential of composites in this application. The results of the structural analyses, which have been investigated by commercial FEA-codes, are presented. The research data resulting from completed testing of components are compared with the simulation results. On the basis of this research a prospect for the application of FRP in the field of side impact protection is given.