Ethanol has been considered as an alternative fuel for diesel engines. On the other hand, injection timing is a major parameter that sensitivity affects the engine performance and emissions. Therefore, in this study, the influence of advanced injection timing on the engine performance and exhaust emissions of a single cylinder, naturally aspirated, four stroke, direct injection diesel engine has been experimentally investigated when using ethanol-blended diesel fuel from 0 to 15% with an increment of 5%. The original injection timing of the engine is 27 degrees crank angle (CA) before top dead center (BTDC). The tests were conducted at three different injection timings (27, 30 and 33 degrees CA BTDC) for 30 Nm constant load at 1800 rpm. The experimental results showed that brake-specific energy consumption (BSEC), brake-specific fuel consumption (BSFC), NOx and CO2 emissions increased as brake-thermal efficiency (BTE), smoke, CO and HC emissions decreased with increasing amount of ethanol in the fuel mixture. Comparing the results with those of original injection timing, NOx emissions increased and smoke, HC and CO emissions decreased for all test fuels at the advanced injections timings. For BSEC, BSFC and BTE, advanced injection timings gave negative results for all test conditions. Copyright (C) 2008 John Wiley & Sons. Ltd.