Biodiesel is a renewable fuel that can be produced from vegetable or animal oil. The main benefit of using biodiesel is its capacity to lower exhaust emissions compared to diesel fuel. Over the last few years, numerous studies have been performed on biodiesel production and its effect to engine performance and emissions. However, in those studies; no attention has been paid in economic analysis of biodiesel usage in engines. In this investigation, various mixtures of biodiesel and diesel fuel have been tested on a four cylinders turbocharged diesel engine. The combustion reaction was determined by using the experimental data. Then, the mass flow rate of each exhaust emissions was calculated, using combustion reaction. The economic analysis was performed considering social cost of emissions, inlet fuel cost and the cost of engine power loss. Because of low diesel fuel price in Iran, the results were determined by ignoring the inlet fuel cost. The technical analysis was also performed considering the engine performance results. The results showed that the 10% and 15% biodiesel-diesel blends (B10 and B15) were more affordable than diesel fuel. The performance results of engine were also acceptable in these blends. The power loss was slight and the highest thermal efficiency was also observed in these blends. All biodiesel blends were more affordable than diesel in emissions economic analysis