The EU Renewable Energy Directives’ sustainability criteria (EU/2009/28) stated that biofuels must offer at least 35% carbon savings compared with fossil fuels. To all Member States, the European Commission has indicated that the use of the transport biofuels have to reach the lvel of 5.75% in 2010. In Latvia, rapeseed methyl ester (RME) is generally supposed to be one of the more valuable possibilities. As the investment are growing, it is important to evaluate the environmental impacts of these productions and to stress the main sources of these impacts. Nowadays, in Latvia the share of biofuels in the transport sector is attested on a value of 0.3% (around 75% biodiesel and 25% bioethanol). The biofuel production in Latvia doubled in the last two year: the total biodiesel production is now around equal to 64 ktonne/year (year 2009). The aim of this paper is to understand and to model the environmental performance of biodiesel produced by rapeseeds under local Latvian conditions. The energy crops have been studied, with regard to their levels of biodiesel productivity. Current Latvian climatic conditions and cultivation parameters have been taken into account. A comparison with the impacts of the related fossil based diesel has been conducted.