A field experiment was conducted at the Agronomy Department Farm, Faculty of Agriculture, Assiut University during 2017 and 2018 seasons to study the response of two sunflower cultivars to foliar spray by different zinc oxide nanoparticles concentrations. The field experiment was carried out in a randomized complete block design (RCBD) using a strip plot arrangement with three replications. Zinc oxide nanoparticles (ZnO NPs) concentrations (control, 100, 200, 300, 400 and 500 ppm) were allotted horizontally, while two sunflower cultivars (Sakha-53 and Giza-102) were assigned vertically. The obtained results showed that number of seeds head-1 , seed index and seed weight head-1 (g), Seed yield (kg fed.-1), oil percentage (%) and oil yield (kg fed.-1) were affected significantly by different zinc oxide nanoparticles concentrations in both seasons, except number of seeds head-1 in the second season. Sunflower plants which were sprayed by 200 ppm ZnO NPs gave the highest mean values of seed yield fed.-1 (1751.99 and 1515.18 kg/fed) and oil yield fed.-1 (676.79 and 600.81 kg/fed) in the first and second seasons, respectively. Furthermore, Giza102 sunflower cultivar gave the highest means for mention traits in the two growing seasons. Also, the interaction between ZnO NPs concentrations and sunflower cultivars had a significant (P≤0.01) effect on the all studied traits in both seasons. Giza 102 plants which were sprayed by 200 ppm ZnO NPs concentration gave the highest mean values of oil yield (723.61and 701.37 kg/fed in the first and second seasons, respectively).