Soil water retention, hydraulic conductivity, aeration, and temperature are affected by soil structure. Moreover, soil structure would affect plant growth and yield by altering soil mechanical resistance and diffusion of nutrients. It is important to identify crops with acceptable yield, which could also maintain good soil quality. Presence of endophytic fungi in a plant could affect soil properties. This study was done in two parts (with lolium and fescue plants) in order to investigate the effect of plant-endophyte symbiosis on structural stability indices and quality of rhizospheric soil. In the first part, the rhizosphere of 22 lolium genotypes of two Iranian and foreign groups (endophyte-infected, E+, and endophyte-free, E–), and in the second part, the rhizosphere of 4 Iranian fescue genotypes (E+ and E–) were studied. In both parts, soil quality indicators such as water repellency, organic carbon, carbohydrate, high energy moisture characteristic (HEMC), shrinkage curve, microbial respiration, total nitrogen and dispersible clay were measured. For all genotypes, quality of the rhizospheric soil was better (due to root exudates) compared to the bulk soil. Organic carbon and carbohydrate were greater in the rhizosphere of lolium c and s E+ genotypes when compared with c, s, Vigor and Speady E– genotypes. Therefore, dispersible clay and microbial respiration were lower in c and s E+ genotypes compared to c, s, Vigor and Speady E– ones. Aggregate stability indices of HEMC showed that lolium E+ genotypes greatly improved the structure of rhizospheric soil compared to E– genotypes and bulk soil. Soil shrinkage curve results confirmed the HEMC results since due to stable structure, the rhizosphere of E+ and E– genotypes had lower coefficient of linear exte ns ibility (COLE) compared to the bulk soil. In the second part, due to root exudates quality of the rhizospheric soil was also better compared to bulk soil. Organic carbon and carbohydrate of the rhizosphere of B and C E+ genotypes were greater than those of B and C E– ones. As a result, dispersible clay and microbial respiration in the rhizosphere of B and C E+ genotypes were lower than those in the rhizosphere of B and C E– ones. HEMC structural stability indices indicated that fescue E+ plant significantly improved the structure of rhizospheric soil when compared with E– one and bulk soil. Relative volume of drainable pores (RVDP), relative stability ratio (RSR) and relative stability index (RSI) especially in the fast-wetting manner were greater in the rhizosphere of E+ genotypes compared to the bulk soil. Moreover, the rhizospheric soil of fescue E– genotypes had higher stability ratio (SR) and volume of drainable pores ratio (VDPR) compared to the bulk soil. The results indicated that shrinkage indices including COLE and relative shrinkage capacity (RShC) in the rhizospheric soil of E+ genotypes were smaller than those in E– ones and then in the bulk soil. The rhizospheric soil of E+ genotypes had greater strength agai ns t shrinking forces compared to the E– ones. Furthermore, slopes of structural and normal shrinkage zones in the rhizospheric soil of E+ genotypes were smaller that those of E– ones and bulk soil, indicating better structure of rhizospheric soil in E+ genotypes. Overall, best genotypes in terms of rhizospheric soil quality are determined to be c6 and s10 genotypes of lolium and endophytic C genotype of fescue. Keywords: Lolium, Fescue, Soil structural stability, High energy moisture characteristic, Dispersible clay, Soil shrinkage curve, Rhizosphere, Root exudates