There is debate about the appropriate design of supplementary airbags for passenger car occupants with high levels of seatbelt use. A theoretical analysis was performed to demonstrate the iikely costs and benefits of US fullsize driver airbags and the smaller European style facebag. This study undertaken for the Federal Office of Road Safety in Australia buiia!s upon previous work in this area. Benefits were determined using Harm Reductions for front seat occupants involved in frontal crashes. A sensitivity analysis was undertaken for different benefit scenarios for the facebag, given the lack of available performance data. Likely costs of the components were derived fi-om information provided by the local automobile manufacturers, part suppliers, and vehicle importers, with adjustments made for fitting to Australian vehicles. The results demonstrate the advantage offullsize airbags overfacebags, even when seatbelt wearing rates are high.