The risk of having a serious traffic accident in Switzerland varies widely dependent on linguistic region. The risk is twice as high in the Italianspeaking canton of Ticino than in the Germanspeaking part, with the French-speaking part somewhere between the two. In addition, the number of victims of serious accidents has declined more significantly in German-speaking Switzerland than in the French- or Italian-speaking parts over the last ten years. Various aspects relating to road safety were investtigated in order to better understand the reasons behind these regional differences. Taking the three linguistic regions into account, around ten sets of statistics contain data on the profiles of traffic accidents, people's attitudes and behaviour in terms of mobility and road safety as well as road infrastructure. This study took into account the three main linguistic regions - German, French and Italian. These regions were defined by the language mainly spoken in the relevant cantons. All data relating to the cantons of Freiburg and Valais was thus assigned to the French-speaking part and that relating to the cantons of Berne and Grisons to the German-speaking part of Switzerland. This study is of an ecological nature since it is based on aggregated data. It is not intended to establish causal links but to gain an overview of the factors which are known to influence the likelihood of accidents. The particular risk factors are as follows: - Socio-demographics - Speed - Alcohol - Seat belts - Helmets - Road infrastructure - Vehicles Risk factors are understood to mean the various elements likely to incur an increased likelihood of accident or to aggravate the consequences of an accident.