Biofuels are being investigated as potential substitutes for current high pollutant fuels obtained from the conventional sources. In the past, fuels were generally selected on the basis of lowest cost relating to the requirements of the engine, and no attention was given to the possible effects of their use on the environment. Recent concerns over the environment, increasing liquid fuel prices and scarcity of supply in the last decade have promoted interest in the development of alternative Sources of liquid energy. The purpose of this research was to evaluate the potential of rapeseed methyl ester (RME) as a liquid fuel for diesel engines in relation to meeting emission requirements. The test results showed that RME and its blends with diesel fuel emitted high CO2 compared to test results on diesel fuel. A very significant reduction in emissions of hydrocarbon (HC) were recorded when running on RME and the blends. HC emissions were noted to increase with increased amount of diesel fuel in the blend. The fuel economy was a little worse when running on RME due to its low energy content. There were no marked difference noted for the exhaust temperatures of the blends, RME and diesel fuel at high speed operation. However, the diesel fuel operation produced high exhaust temperatures at low engine speed. Lubricating oil analysis showed reduction in viscosity indicating oil dilution. (C) 2003 Elsevier Ltd. All rights reserved.