This paper concerns the development and validation of a three-dimensional mathematical model representing a motorcycle with rider. As part of this development, several motorcycle to barrier tests were performed at the laboratories of the TNO Crash-Safety Research Centre and several measurements were carried out, including measurements to determine the inertia properties of the motorcycle segments. Results of two full scale tests involving a passenger car were then applied to validate the model in a more realistic crash environment.The resulting MADYMO motorcycle model consists of 7 bodies linked to each other by joints and spring-damper type elements. Special attention was given to the mathematical representation of front fork, front wheel and gastank. A 50th %ile Part 572 dummy with pedestrian pelvis and legs represented the rider. For representation in the model an existing dummy database was updated.Computer simulation of motorcycle rider behaviour during a collision event proved to be far more difficult than the simulation of passenger car occupants, due to the contact interaction between three moving ojects and the complex way in which motorcycles and their riders behave after impact. Nevertheless, the simulation results obtained are very promising. The main drawback of the simulation model as presented here seems to be the underestimation of the energy absorption by the motorcycle in the case of relatively large deformations. Bringing in extra measurement results and applying recent features of the MADYMO program can only improve the simulation results. It is believed that the motorcycle with rider model developed can provide better understanding of the collision mechanisms involved and predict trends as far as passive safety devices feasibility studies are concerned.