A pot experiment was carried out in a greenhouse at the College of Agriculture, Isfahan University of Technology in 2013 to evaluate the effects of different levels of nitrogen on the response of barley genotypes to salinity. The experiment was arranged as factorial based on a completely randomized block design with three replications. In this experiment, nine barley genotypes (CB-84-10, Yousef, Reyhan-03, Line-4 salt tolerant, Line-5 salt tolerant, Nosrat, Loot, Bahman and Fajr-30) were evaluated under two levels of salinity (0 and 150 mM of NaCl) and two levels of nitrogen (0 and 46.2 mg/kg pot soil). Plant height, number of tillers, leaf area, shoot and root dry weight, photochemical efficiency of PS II (Fv/Fm), the concentration of nitrogen, potassium, potassium/sodium ratio in shoots were reduced, but leaf yellowness intensity, shoot/root dry weight ratio, SPAD index, the content of sodium, proline and soluble carbohydrates in shoot and the concentration of nitrogen in roots were increased under saline treatment. With an increase of soil nitrogen, the values of plant height, number of tillers, leaf area, shoot dry weight, shoot/root dry weight ratio, SPAD index, photochemical efficiency, the concentration of potassium, potassium/sodium ratio in shoot and the concentrations of nitrogen in shoot and roots were increased, while, that of leaf yellowness intensity was reduced. The interaction between salinity and nitrogen was significant on the number of tillers, leaf area, leaf yellowness intensity, shoot dry weight, SPAD index, the content of potassium and soluble carbohydrates in shoot and the concentrations of nitrogen in shoot and roots. Under non-saline condition, shoot dry weight was increased by 24% as a result of nitrogen application, while, the difference between the two levels of nitrogen was not significant in this regard under saline condition. The interaction between salinity and genotype was significant on the number of tillers, root dry weight, the content of sodium, potassium/sodium ratio and the content of proline in shoot and the concentration of nitrogen in roots. Based on the reductions in shoot dry weight, of barley genotypes, Nosrat was the most tolerant and Loot was the most sensitive genotype in response to salinity. There was a significant correlation between the reduction in potassium/sodium ratio in shoots under salt condition and salt tolerance of barley genotypes. The results of this experiment showed that there was considerable variation among barley genotypes in response to salinity. Also, nitrogen application resulted in increased growth of barley genotypes under non-saline condition; however, under situation of this experiment, plant growth was not significantly improved by nitrogen application under saline condition.