Promoting the use of renewable energy sources is object of a strong commitment by the European Union and Italy is committed through the National Renewable Energy Action Plan (PAN) to cover its end-use energy consumptions with more than 20 Mtoe energy obtained from renewable sources by 2020. The development of renewable sources in electricity production is a strategic asset within the National Renewable Energy Action Plan. Given the growing potential of using energy from biomass, it is of primary importance to define a framework of the environmental potential impacts resulting from using biomass. Objective of this paper is to provide an overview of the potential impacts resulting from the use of different types of biomass for electricity production, using the methodology of Life Cycle Assessment (LCA). To this end a LCA of electricity produced in Italy by different kind of biomass has been carried out, considering solid biomass (both urban wastes and wood chips from SRF), liquid fuels (different kind of biodiesel and vegetable oil) and biogas (from wastes, from dedicated energy crops and from sludge). Despite of their positive effects on Green House Gas Emissions, all kind of energy from biomass perform worse in many other analyzed indicators (e.g Air Acidification, Photochemical Oxidant Formation, Human Toxicity) when compared to energy from other renewable resources (e.g. from wind energy) and even if compared with the LCA of electricity produced from Natural Gas Combined Cycle Power Plant (considered the Best Available Fossil Fuel Technology). In order to verify if the environmental benefits at global scale (reduced gas emission an resource depletion) exceed the environmental impacts at local and regional scale, we decided to aggregate results in a unique indicator: external costs. To this end we used the simplified methodology proposed by the European Environmental Agency. We first quantified the atmospheric emissions of CO2, N2O, CH4, NOx, SOx, PM25, NMVOC and NH3 of all Life Cycle of electricity from bioenergy. We than identified which kind of electricity production from fossil fuels is substituted by the new production from bioenergy. We identify the substituted technologies. According to the Italian Electric Energy market, we considered the mix of technologies that have been marginal in the market while the electricity is produced by bioenergy. We than quantified the atmospheric emissions of CO2, N2O, CH4, NOx, SOx, PM25, NMVOC and NH3 of all Life Cycle of electricity from this fossil fuel mix, and we compared their external costs with those of the mix of bioenergy used in Italy. We find out that the bio energy external benefits at global scale due to reduced greenhouse gas emissions do not exceed the increased external costs at regional and local scale leading, at least as far as atmospheric emission are concerned with, to an increase in environmental external costs.