Pollination is very important for achieving an economical production in hazelnuts. This study was conducted as a factorial randomized complete block design with three replications. In this study, the effects of three pollinizers (Pashmineh, Gercheh and Shastak) on nut and kernel characteristics of some hazelnut cultivars (Rounde, Fertilede coutard and Gerdeshkvarat) were investigated. The results of the flowering phenology showed that all cultivars were protanderious. The time of the male flowers opening in Ronde and Fertilede coutard was from early January to late January and in Gerd Eshkvarat was from mid-January to late January. The opening time of the female flower was variable from mid-January in Ronde to late February in Fertilede coutard. The results showed that the quantitative traits of nut and kernel were strongly influenced by pollen sources. Using stronger and more viable pollen grains of Gercheh pollinizer, the heaviest nut and kernels, the highest percentage of kernel production, and the lowest percentage of blankness kernels were 3.64, 1.48, 48.69, and 13.94, respectively. However, using Shastak pollen grains, the weight of the nut and kernel was decreased by 2.44 % and 1.22 %, respectively, and the blankness percentage of kernel was increased by 26.48 %. The amount of blankness increased dramatically to 87.51 % in self-pollination and nut and kernel weight significantly reduced to 1.27 and 0.22 g, respectively. In general, pollen grain had effects on some fruit characteristics such as nut and kernel weight, percentage of blankness and kernel production, and pollen grain had no significant effect on nut and kernel shape. The highest overlap of male flowers opening in pollenizer genotypes with female flowers of Rounde, Fertilede coutard, and Gerdeshkvarat was observed in Gercheh.