The addition of ethanol to a blend of vegetable oil (VO) and diesel, in general, has been found to improve the compression ignition diesel engine performance. In the present investigation, the influence of ethanol on Mesua ferrea Linn oil–diesel blend has been studied. Mesua ferrea Linn trees, abundant in the northeastern states of India, have the potential to supplement the fossil diesel. The blend studied is composed of 30% Mesua ferrea Linn oil and 70% diesel by volume (VO30). Ethanol is added 5 and 10% by volume to VO30 binary blend to form two ternary blend VO30E05 (5% ethanol and 95% VO30) and VO30E10 (10% ethanol and 90% VO30). Experiments have been carried out in a four-stroke, single cylinder, water cooled, stationary diesel engine at various engine loads. The addition of ethanol results in an increase of brake thermal efficiency up to 1.5% as compared to neat VO30. The brake specific fuel consumption of the engine increases on an average by 1.8 and 3% with the use of 5 and 10% ethanol, respectively. The use of ethanol results an increase of CO and HCemissions while a decrease of NOX emission