Salinity is a major abiotic stress limiting growth and productivity of plants in many areas of the world due to increasing use of poor quality water for irrigation and soil salinization. Moreover, salinity is an important factor that limits the development of urban landscape, especially in arid and semi-arid regions. Rosmary, as a medicinal - ornamental plant, is used in gardens and for xeriscaping and landscaping designs. Arbuscular mycorrhizal fungi, one of the soil beneficial microorganisms that can increase the tolerance of plants to stress. The present study was conducted to assess the effects of mycorrhizal fungi on improving salinity tolerance in Rosmary plant. A factorial experiment was arranged in a completely randomized design with four levels of sodium chloride (0, 50, 100, 150 mM) and four treatments of mycorrhizal fungi (non-inoculation, Rhizophagus intraradice s , Funneliformis mosseae species and combination of two species) with three replications. Results showed that the highest percentage of root colonization was observed for the mixture of two species (54.27%) and the lowest percentage of colonization associated with F. mosseae (47.06%). Mycorrhizal symbiosis increased plant growth, plant root, relative water content (RWC), promoted the accumulation of biomass and chlorophyll content and improved antioxidant capacity, regardless of salinity level. Results showed that salinity stress was adversely effected growth parameters of rosemary plants. However, our results revealed that the inoculation of plants with mycorrhizal fungus resulted in improved growth and decreased sodium toxicity under NaCl. Mycorrhizal plants had higher POD, CAT, and APX activities, photosynthesis pigments, Fv/Fm, proline content, but lower electrical linkage and Na + concentration in leaves of rosemary plant under both saline and non saline conditions. Results from the present study indicate that mycorrhizal fungus symbiosis can enhance photosynthesis and ROS scavenging capabilities and increase root growth and RWC of leaves to alleviate salinity stress in rosemary plant. Key words: Mycorrhizal fungus, Salinity stress, Rosemary, Colonization