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Plant growth and development are adversely affected by salinity. In order to evaluate the effects of different salinity levels and application of chitosan on some growth parameters, photosynthesis pigments and essential oils content and yield of moldavian balm (Dracocephalium moldavica L.), a greenhouse experiment was carried out as a factorial based on the completely randomized design (CRD) and three replications. The first factor was three levels of salinity stress included 0, 25 and 50 Mm NaCl and the second factor was application of chitosan (0, 0.25, 0.5 and 1 % w/v). The studied traits include the morphological (plant height, shoot fresh and dry weight, leaf fresh and dry weight and inflorescence length), chlorophyll fluorescence (Variable fluorescence, maximum chlorophyll fluorescence yield, Water degradation complex), photosynthesis pigments (chlorophyll a and b, carotenoid) and also essential oil content and yield. The results demonstrated that all morphological traits and some of physiological characteristics including chlorophyll fluorescence indices, chlorophyll a, and chlorophyll b and carotenoid contents significantly decreased with increasing the salinity level. In addition, the results showed that with application of chitosan in the salinity conditions, all morphological traits, antioxidant enzymes activity, and chlorophyll fluorescence (Variable fluorescence, maximum chlorophyll fluorescence yield, Water degradation complex, Y (II)) parameters improved compared with control. Furthermore, foliar application of chitosan increased the essential oil and yield under salinity stress condition. It seems that chitosan has a positive effect to overcome effects of salinity stress and might be help to increasers essential oil yield on medicinal plants.