The current article elaborates the various emission characteristics of jatropha oil methyl ester with fossil diesel in a direct injection (DI) diesel engine at various loading conditions for different volume proportions of test fuels. Results depicted that CO, HC, and NO emission were the lowest for jatropha biodiesel compared with diesel, while smoke opacity was more for pure biodiesel due to the high viscosity, low volatility, and low heat content compared with diesel. Jatropha biodiesel may be beneficial for reducing greenhouse gas emission without any engine modification.