Abstract A mathematical sled model that included a BIOSID dummy was used to evaluate the potential injury reducing benefits of padding or airbags in side impacts. The side impact simulations were carried out using the crash victim simulation software MADYMO2D. The model has been validated against mechanical sled tests at two impact velocities: with padding, or with airbags mounted to the door. The airbags were filled with compressed air and had varying initial (over) pressures and ventilation areas. The protective system resulting in the lowest injury measures for the dummy was thus determined. The lowest TTI was obtained with the airbag with 0 kPa initial over pressure and 1500 mm2 ventilation area, while the lowest chest deflection and chest VC were obtained with an airbag with 40 kPa initial over pressure and 2000 mm2 ventilation area. The risk of the head impacting the side window was significantly reduced with the addition of an airbag. It was found that the airbag has to be at least 120 mm thick when fully inflated in order to significantly reduce injury measures. The arm and shoulder of the occupant have to be engaged in the impact. The model of the BIOSID dummy was found to be a very valid and valuable tool for evaluating the protective effect of padding and airbags in the side door.