Increasingly restrictive emission regulations and renewed focus on energy efficiency drive the current diesel researches to find fuels with better properties to affect combustion process properly. This study investigates the effects of Tri-aromatic utilization on combustion, performance and exhaust characteristics of a direct injection (DI) diesel engine. The engine experiments were run at first and fifth modes of 8-modes steady-state emission test procedure (ECE-R96). As aromatic content of fuel increases, CN decreases. The effect of Tri-aromatic is similar to the effect of other aromatic components in the diesel fuel composition on CN. The results show that the brake specific fuel consumption (BSFC) decreases, the thermal efficiency improves, NOx emission increases and smoke emission decreases when diesel engine fueled with a blend of 20% by volume of Tri-methyl benzene and 80% by volume of diesel fuel. From the combustion analysis, it is found that the ignition delay almost does not change, and the total combustion duration prolongs for the blended fuel in comparison with the commercial diesel fuel. (C) 2014 Elsevier Ltd. All rights reserved.