This final report for the Swiss Federal Office of Energy (SFOE) deals with the results of a study that evaluated the environmental impact of the entire production chain of fuels made from biomass and used in Switzerland. Firstly, the study supplies an analysis of the possible environmental impacts of biofuels that can be used as a basis for political decisions. Secondly, an environmental life cycle assessment (LCA) of various biofuels is presented. In addition, the impacts of fuel use are compared with other uses for bioenergy such as the generation of electricity and heat. The methods used in the LCA are discussed, including the Swiss method of ecological scarcity (Environmental Impact Points, UBP 06), and the European Eco-indicator 99 method. The results of the study are discussed, including the finding that not all biofuels can reduce environmental impacts as compared to fossil fuels. The role to be played by biofuels produced in an environmentally-friendly way together with other forms of renewable energy in our future energy supply is discussed.