The Kyoto protocol and the EU Directive 2009/28/EC focus their attention on the reduction of greenhouse gases (GHG) emissions. The use of biofuels in the transport sector is one of the main measures proposed. This paper evaluates the environmental impact, in terms of GHG emissions, of the production and use of rapeseed biodiesel, comparing the results with conventional diesel. The methodology used is the Life Cycle Assessment (LCA). The results of the analysis show that the production of rapeseed biodiesel entails a substantial reduction of the GHG emissions compared to the diesel production system. Furthermore, the agricultural phase is identified as the process which causes the largest amount of GHG emissions in biodiesel life cycle. Therefore it could be possible to improve further the environmental performance of biodiesel intervening properly at that stage.