The effect of engine emissions due to using fossil fuels and its management is one of concerns cross the world. Recently, biodiesel and ethanol are well recognized as appropriate alternatives for diesel engines. In various countries bioethanol and biodiesel have attracted great attentions as alternative fuels in application and research because of renewability and environmentally friendly properties and reduction of using fossil resources. Here the benefits and limitations of usage the biofuels in diesel engine were reviewed. The effects of biodiesel-diesel, ethanol-diesel, and biodiesel-ethanol diesel blends on diesel engine were reviewed. Biodiesel and bioethanol are used in diesel engines mainly due to lower exhaust emissions and hence less environmental pollutions. As biodiesel and ethanol usage in diesel engines are some limitations, the optimization of biofuels components in the fuel blends of diesel engines is necessary. So, optimization of using biofuels in diesel engines as well as using new additives and analytical approaches was recommended in future studies.
