This investigation was conducted in two separate experiments in greenhouse to evaluate the effects of ordinary and nano forms of zinc oxide on the response of wheat cultivars to salinity. Each experiment was arranged as factorial in a randomized complete block design with three replications. Nutrient treatments in both experiments were consist of the supply of ordinary and nano forms of zinc oxide in nutrient solution. In the first experiment 20 cultivars of wheat (Shole, Sorkh tokhm, Adl, Hirmand, Azadi, Bayat, Estar, Roshan, Niknejad, Back cross Bahare roshan, Iniya, Moghan2, Sistan, Line 9 shori, Tabasi, Karaj 1, Pishtaz, Chenab, Kavir, Chamran) were studied at two levels of salinity (0 and 150 mM NaCl). In the second experiment four wheat cultivars (Niknejad, Roshan, Iniya, and Moghan2) were evaluated under three salinity levels (0, 75 and 150 mM NaCl). These four cultivars were chosen based on their substantial variation in terms of the response to the application of nano form of Zno in the first experiment. With an increase in salinity level leaf area, shoot and root dry weight, leaf chlorophyll content, the concentration of potassium and zinc in shoot were decreased, but the concentration of sodium in shoot, the shoot/ root ratio, the activities of catalase, peroxidase and ascorbate peroxidase were increased. The interactions between salinity and cultivars were significant on shoot dry weight and on the activity of antioxidant enzymes. The extent of reductions of shoot dry weight in wheat cultivars ranged from 20 to 41 percent. Cultivars Adl and Hirmand were identified, respectively, as the least and the most sensitive cultivars to salinity. Among tested cultivars the extent of increases in the activity of antioxidant enzymes in response to salinity ranged from 2.37 to 4.80 folds for catalase and from 2.24 to 5.93 folds for ascorbate peroxidase and from 1.72 to 6.10 folds for peroxidase, respectively. There was significant variation among cultivars in response to Zno application. Supply of plants with the nano compared to ordinary form of zinc oxide increased shoot dry weight in cultivars Sistan, Kavir, Sorkh tokhm, Hirmand, Iniya and Niknejad but instead decreased shoot dry weight in cultivars Moghan2 and Roshan. The difference between the two forms of zinc oxide was not significant in this regard for other tested cultivars. The activity of antioxidant enzymes were increased as plants were supplied by nano form of zinc oxide and the extent of the increases was smaller in peroxidase than in catalase and ascorbate peroxidase. The results from this experiment showed that there were significant differences among wheat cultivars in response to salinity and the application of nano form of zinc oxide. Key words: wheat, salinity, zinc oxide, nano-particles, antioxidant enzymes.