Abstract: Seedling of two sorghum genotypes (Payam and Sistan) and four wheat genotypes (Bolani, Hirman, Star and Toss) were grown in Hoagland nutrient solution containing 0, 100 and 200 mM NaCl in controlled environment. Antioxidant activities like catalase (CAT), ascobrate peroxidase (APX) and guaiacol peroxidase (GPX) and osmolyte concentrations, proline and soluble carbohydrates were determined in the leaves 20 days after induction of salinity stress. Results showed that the activity of APX, GPX and CAT increased in both sorghum genotypes. Wheat genotypes showed significant differences during the experimental period. By increasing NaCl levels from 0 to 200 mM the activity of APX and GPX decreased, but the activity of CAT increased in all wheat genotypes. At the 100 mM NaCl, the CAT activity in wheat genotypes was higher compared with that in 200 mM NaCl. The increase in salinity stress increased total soluble carbohydrates and proline both in wheat and sorghum genotypes. Results in this study showed sorghum genotype displayed better osmotic adjustment and antioxidant compounds under salt stress and the efficiency of Sistan was better than Payam. Contrarily in wheat, osmotic adjustment (carbohydrate and proline accumulation) was much more effective than antioxidant enzyme activity.