This paper reports the results of an experimental investigation on the combustion characteristics and exhaust particulate emissions of a GDI high performance engine, fuelled with blends of bio-ethanol and European gasoline fuel. The engine is a 4-cylinder, 4-stroke, 1750 cm₃ displacement, and turbocharged. The engine was operated at fixed speed and load, namely 1500 rpm and 110 Nm, and fuelled with gasoline (E0), ethanol (E100) and two blends 50% v/v (E50) and 85% v/v (E85) of ethanol in gasoline. Two fuel injection strategies were investigated: homogeneous charge and stratified charge combustion mode. The study mainly focuses on the effects of fuel injection strategy and ethanol upon the emissions of particulate matter (PM), in terms of mass, number concentration and size distribution. The particle size distribution was measured using a differential mobility spectrometer (Cambustion DMS500), which allows measuring the electrical mobility diameter of particles in the size range 5-1000 nm with high time resolution (10 Hz). Smaller particles and lower total mass were emitted from the engine fuelled with pure ethanol with respect to gasoline. On the other hand, using the blends E50 and E85, a large increase of the number concentration of particles in the accumulation mode was observed. Furthermore, the PM mass increased largely under the stratified combustion mode with E50.