The root endophytic fungus Piriformospora indica has been shown to increase resistance against abiotic salinity stress in some crop plants: Vicia faba, Lupinus termis, Arachis hypogaea and Hibiscus sabdariffa. The presence of the fungus reduced the effect of the salinity on the growth rate; and enhanced the photosynthetic processes and protein contents. Moreover, water relations were improved under the effect of the fungus. It was found that, the treated plants by Piriformospora indica reduced the negative effects of salinity on the growth of these plants. From the obtained results, it can be concluded that, Vicia faba, Lupinus termis, Arachis hypogaea and Hibiscus sabdariffa can be cultivated in moderated salinity lands in the presence of root endophyte fungus Piriformospora indica.