Effect of Karanja biodiesel (Karanja oil methyl ester; KOME) and its blends on engine performance, emissions and combustion characteristics in a direct injection compression ignition (DICI) engine of a medium size utility vehicle with varying engine speed and load has been investigated. Maximum torque attained by 10% and 20% KOME blends were higher than mineral diesel, while higher biodiesel blends produced slightly lower torque. BSFC for lower KOME blends was comparable to mineral diesel however BSFC increased for higher biodiesel blends. BSCO, BSHC and smoke emissions of Karanja biodiesel blends were lower than mineral diesel but BSNOx emissions were slightly higher. Comparative investigation of performance, emissions and combustion characteristics of Karanja biodiesel blends and mineral diesel showed that up to 20% Karanja biodiesel blend can be utilized in an unmodified DICI engine. (C) 2013 Published by Elsevier Ltd.