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The present study investigated the regulatory roles of exogenous salicylic acid (SA) in physiology, antioxidant defense systems and yield of wheat under different salt stress conditions. The experiment was conducted with two varieties, 'BARI Gom 21' and 'BARI Gom 25' and ten salt stress treatments viz. control (without salt), SA (1 mM salicylic acid), S50 (50 mM NaCl), S50+SA (50 mM NaCl with 1 mM SA), S100 (100 mM NaCl), S100+SA (100 mM NaCl with 1 mM SA), S150 (150 mM NaCl), S150+SA (150 mM NaCl with 1 mM SA), S200 (200 mM NaCl) and S200+SA (200 mM NaCl with 1 mM SA). Leaf relative water content (RWC) and chlorophyll (chl) content reduced due to salt stress. The malondialdelyde (MDA) and H2O2 were increased under the stress condition. The ascorbate (AsA) content, reduced glutathione (GSH) and GSH/GSSG ratio were reduced by salt stresses (50, 100, 150 and 200 mM NaCl, respectively). But the glutathione disulfide (GSSG) amount increased with an increase in the all levels of salinity. The ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR) and catalase (CAT) activities showed a significant reduction in response to salt stress, but CAT increased only at 100 mM stress condition. The glutathione S-transferase (GST) and glutathione reductase (GR) activity increased significantly with severe salt stress (200 mM NaCl). Also the activity of peroxidase (POD) was decreased with increasing salinity level. At harvest, salt stresses reduced the effective tiller hill-1, 1,000 grain weight, grain yield, straw yield, biological yield and harvest index for both of varieties. However, the number of non- effective tiller hill-1 significantly increased in response of salt stress. Exogenous 1 mM SA application with salt stress improved physiological parameters, yield and reduced oxidative damage in both cultivars, where 'BARI Gom 25' showed better tolerance. SA application could not improve physiological parameters and yield at extreme level of salt stress (200 mM NaCl). [ABSTRACT FROM AUTHOR]