The purpose of this study was to investigate particle emission characteristics from a spark ignition direct injection (SIDI) engine fueled with ethanol-gasoline blends. Particulate matter (PM) from internal combustion engine is a complex mixture of substances deemed harmful for the human body. Consequently, they are regulated by stringent legislation. According to the Euro-6 regulation, the standard for particle number (PN) emissions of SIDI vehicles is 6.0 x 10(11) N/km. Recent studies have reported that SIDI engines, renowned for their feasibility in reducing CO2 emissions, could produce excessive amounts of PM due to its structural characteristics. For this reason, there have been many studies on reducing PM emissions from SIDI engines to satisfy strict emission standards. Because ethanol contains an oxygen atom in each molecule, it has a significant influence on combustion performance and characteristics of vehicular discharge, including PM. This study focused on the effect of intermediate ethanol blends from E0 (pure gasoline fuel) to E20 (gasoline fuel with 20% volume of ethanol) on engine performance, size-resolved particle emissions, and engine startability. Particle emission characteristics including particle number and size distribution at part-load test and start performance were investigated with operation points, fuel pressure and injection timing. (C) 2015 Elsevier Ltd. All rights reserved.