Abstract: Since several years entomopathogenic fungi, specifically Beauveria bassiana,Lecanicillium lecanii, and Metarhizium anisopliae, have been reported as organisms able tocolonise different plant species and plant parts, thereby maintaining their entomopathogenicpotential against various insect pests. This review discusses different aspects of the use of theseentomopathogenic fungi as a plant protection strategy. Although the endophytic growth andestablishment of these fungi can be initiated either by foliar spore application or by incorporationinto the soil, the growth and maintenance within the plant tissues need to be guaranteed duringthe whole cropping season. New or improved formulation strategies need to be developed toenhance the colonization process of these organisms in the different plant tissues. So far theinfection process of herbivores feeding on colonized plant tissues has not been studied in detailand mycosis has not been reported in all cases. Whether production of mycotoxins by endophyticentomopathogenic fungi may create a problem for humans consuming colonized plant parts needsto be addressed in forthcoming studies, as well potential non-target effects on natural enemies.The potential of endophytic entomopathogenic fungi as a new strategy for plant protection isdiscussed in the light of these open questions.