In this work, ethanol was mixed with biodiesel-diesel blends and the effect of ethanol concentration on diesel emissions was investigated. Both low and high concentrations of ethanol were studied. Ethanol concentrations were varied at 3%, 5%, 15% and 25% in biodiesel-diesel-ethanol (BDE), while biodiesel and diesel concentrations were maintained equal (BDE3, BDE5, BDE15 and BDE25). Emission characteristics for biodiesel-diesel-ethanol blends were compared to baseline curves of diesel as a function of engine load. (C) 2013 Elsevier Ltd. All rights reserved.