Background: Arbuscular mycorrhizal fungi (AMF) have the potential to optimize the rhizospheric soil characteristics considerably thereby affecting plant growth.

Objectives: The aim is to investigate the effects of fungi inoculation (Glomus intraradices) on morphological, physiological and phytochemical traits of Rosemary (Rosemarinus officinalis L.) under salt stress.

Methods: A factorial experiment was conducted on the basis of randomized complete blocks design in three replications at the Institute of Medicinal Plants in the Academic Center for Education, Culture and Research (ACECR). The mycorrihzal fungi in two levels (inoculation and non-inoculation) and saline conditions in five levels (EC of 0, 2, 4, 6 and 8 dS.m^-1) were the two studied factors. The essential oil content and its components were measured with Clevenger-type apparatus and GC/Mass and GC.

Results: The results showed that the interaction effect of fungi inoculation and salinity was significant (P≤0.01) on morphological and phytochemical traits. The highest number of shoots per plant in fungi inoculation and salinity of 2 dS.m^-1, number of leaves per plant in fungi inoculation and salinity of 6 dS.m^-1, stem diameter in non-inoculation and salinity of 8 dS.m^-1 was recorded, while the maximum leaf width in non-inoculation and salinity of 2 dS.m^-1, stems fresh weight in fungi inoculation and control and, roots fresh and dry weight in treatment of fungi inoculation for both traits and salinity of 8 dS.m^-1 and 6 dS.m^-1 was recorded, respectively. Also, interaction effect of fungi inoculation and salinity significantly increased essential oil content and its components.

Conclusion: The phytochemical and morpho-physiological traits of rosemary were improved due to inoculation of mycorrhizal fungi under saline conditions.