Compression ignition ( C. I.) engine fuelled with rapeseed oil methyl ester (RME) as the main fuel and bioethanol injected into the inlet port for supporting burning of RME was developed and investigated. The concept of ethanol injection depends on the thesis, that after ignition from burning RME droplets, ethanol-air mixture burns very quickly and promotes combustion of the main fuel droplets, resulting in a shorter combustion period. Experiments carried out with the use of a one-cylinder direct injection diesel engine adapted to ethanol injection enabled to appreciate the influence of ethanol energy fraction on performance, emission and combustion parameters. Significant decrease of CO2 and smoke level was obtained in whole range of load and-also CO and HC emission, while for low load only - NOx emission. The higher the fraction of ethanol, the longer the ignition delay but the shorter the overall time of combustion.