An experiment was carried out in a glasshouse at the college of agriculture, Isfahan University of Technology, during September and October 2009 using hydroponic solution to evaluate the effects of iron nutrition on the response of sunflower genotypes to salinity. The experiment was arranged as factorial based on a completely randomized design with four replications. In this experiment four sunflower genotypes were studied at three salinity level (0, 60 and 120 mM of NaCl) and three iron concentration (0, 50 and 100 mM). Plant height, leaf area, shoot and root dry weight, shoot/ root dry weight ratio, chlorophyll content, maximal photochemical efficiency (Fv/ Fm), the rate of photosynthesis , stomatal conductance , potassium concentration, the ratio of K/Na in shoots and roots were reduced as the level of salinity was increased. However, the concentrations of sodium in shoots and roots and the ratio of chlorophyll a/ chlorophyll b were increased under saline treatments. The interactions between salinity and genotype were significant on the leaf dry weight and the rate of photosynthesis. While the differences among genotypes in terms of leaf dry weight and the rate of photosynthesis were significant in treatments with 0 and 60 mM salt, there were no significant differences among genotypes at 120 mM saline solution. There was an significant increase in the values of leaf area, shoot and root dry weight, the ratio of shoot/ root dry weight, chlorophyll content of leaves and the rate of photosynthesis as the level of iron concentration was enhanced in nutrient solution from 5 to 50 mM. With a further increase of iron concentration from 50 to 100 mM, however, there were no significant changes for these traits. The interactions between salinity and iron concentration were significant on the leaf dry weight, the rate of photosynthesis, maximal photochemical efficiency (Fv/ Fm) and iron concentration in the shoot and root tissues. There was an increase of 41 percent in leaf dry weight when the concentration of iron was increased from 5 to 100 mM in non saline solution. However, this increase in leaf dry weight was 63 percent in 120 mM saline solution. The results from this experiment shows that salt stress can significantly reduce the growth of sunflower plants and the sufficient concentration of iron in nutrient solution may alleviate the negative effects of salinity. Key words: Salinity, sunflower genotypes, hydroponic solution, nutrients