Due to the increasing demand for fossil fuels and environmental threat, a number of renewable sources of energy have been studied worldwide. In the present investigation a high linolenic linseed oil methyl ester has been investigated in a constant speed, DI diesel engine with varied fuel injection pressures (200, 220 and 240 bar). The main objective of this study is to investigate the effect of injection pressures on performance, emissions and combustion characteristics of the engine. The test results show that the optimum fuel injection pressure is 240 bar with linseed methyl ester. At this optimized pressure the thermal efficiency is similar to diesel and a reduction in carbon monoxide, unburned hydrocarbon and smoke emissions with an increase in the oxides of nitrogen was noticed compared to diesel. The combustion analysis shows that, the ignition delay is lower at higher injection pressures compared to diesel and the peak pressure is also higher at full load, The combustion duration was almost same at all the injection pressures. It is concluded that linseed methyl ester at 240 bar injection pressure is more efficient than 200 and 220 bar, except for nitrogen oxides emission. (C) 2008 Elsevier Ltd. All rights reserved.