In this study, the performance, combustion and injection characteristics of waste (frying) palm oil (WPOME) and canola oil (COME) methyl esters have been investigated, and compared to petroleum based diesel fuel (PBDF) as reference fuel. In order to determine the performance, combustion and injection characteristics, the experiments were carried out in a six-cylinder, naturally aspirated, direct injection diesel engine at 1000, 1500, 2000 rpm constant engine speeds under the full load condition. When the test engine was fueled with WPOME and COME, while the brake power and thermal efficiency reduced by 2%, the brake specific fuel consumption increased by 6% on average. When the cylinder gas pressure, heat release and fuel line pressure graphics of the methyl esters and PBDF are investigated, it will be seen that the combustion graphics of the fuels seem similar to each other with respect to mechanical loading. However, by using methyl ester, very little combustion differences took place such as earlier premixed combustion phase, shorter ignition delay and maximum cylinder gas pressure region closed to top dead center (TDC) compared to PBDF. In addition, when the test engine was fueled with methyl esters, the start of injection timing took place earlier than that of PBDF. The with usage of the methyl esters changes in the injection and combustion characteristics, and fuel properties of the methyl ester caused reductions in carbon monoxide (CO), unburned hydrocarbon (HC) emissions and smoke opacity, but they caused to increases in nitrogen oxides (NO(x)) emissions.