In this study, the effect of gasoline fumigation on the energy and exergy balance of a DI diesel engine fueled with waste cooking oil biodiesel and diesel blend (B20) is experimentally investigated and theoretically studied. To, have a comprehensive analysis, diesel and B20 were considered as two baseline fuels and gasoline fumigation was induced at two different ratios. The obtained results reveal that gasoline fumigation increases the energy and exergy efficiency at medium and high loads to about 5% for diesel baseline fuel, while the energy and exergy efficiency decreases slightly in case of B20 fuel with gasoline fumigation. For all operating points, the percentage of energy and exergy transfer through the exhaust gases decreases by an average of 2.6% and 6.4%, respectively in case of using gasoline fumigation for both diesel and B20 fuels. Moreover, the destructed exergy of the engine operating on B20 and the fumigated gasoline was higher than that of diesel and B20 by about 2.4% on the average. It could be concluded that the combination of B20 and gasoline fumigation might be used as a substitute for diesel fuel in diesel engines under high loads, with higher exergy efficiency and lower exhaust exergy losses. (C) 2017 Elsevier Ltd. All rights reserved.