This experiment was carried out at North Sinai Research Station Farm, 30 Km East El-Arish City (North Sinai Governorate), Desert Research Center, Egypt during the two consecutive seasons of 2014 and 2015, to study the effect of spraying with different concentrations of salicylic acid on vegetative growth parameters, essential oil yield and chemical constituents of Origanum syriacum, L. plant under saline water irrigation (about 3000 ppm) stress conditions. This experiment included 4 treatments, which were four concentrations of salicylic acid (0, 500, 750 and 1000 mg/l) sprayed on plants. Treatments were arranged in a complete randomize design with three replicates. The results indicated that all the measurements (plant height, herb fresh and dry weights per/plant, herb fresh and dry weights per feddan, oil percentage of herb, oil yield per plant and per feddan as well as total nitrogen, phosphorus and potassium percentages) were increased with increasing the concentration of salicylic acid, as there was a direct relationship between the increase in the concentration of salicylic acid and the increase in the characteristics under study.  So that our recommendation is to spray Origanum syriacum, L. plants with 1000 mg /l of salicylic acid to gain the maximum yield of herb an essential oil from this plant.