Abstract
The aims of this study are to determine: (1) the traffic safety effect of the Dutch seat belt law that became mandatory for drivers and front seat passengers since 1 June 1975; and (2) the resulting belt use increase. Time series of trends in safety figures for the 1968-1984 period are analyzed using the Structural Time Series Modelling (STSM). It was not possible to provide a conclusive evidence of how many lives have been saved as a result of the mandatory seat belt law. However, an indication could be given of a decrease in car occupant fatalities of about 7% in the first twelve months after the implementation of the mandatory seat belt law.