This study evaluated the effect of artificial pollination on pistachio trees in an orchard at a low ratio of male to female trees in Qazvin province, Iran, over the years 2012-2013. Experimental factors included three female cultivars (Akbari, Owhadi, Kalebozi) and three types of pollinizer (Control, GA, and GB) with three replications. In each female tree, two branches were selected in the northern and southern directions and bagged before flowering. When stigma was ready to receive pollen, artificial pollination was carried out using the male genotypes GA and GB. The traits of some fertilized flowers per cluster, initial and secondary abscission of flowers and fruits, number of fruits per cluster, nut dry weight per cluster, nut dimension, blankness percentage, and non-split nuts percentage were investigated. The results indicated that artificial pollination in three stages after flowering not only increased the quantitative traits such as number of flowers and fruits per cluster but also reduced the percentage of non-split fruits and blank fruits in all cultivars. The highest and lowest numbers of fertilized flowers were obtained by pollination with GA (91.67) and open pollination (73.89), respectively. Besides, the lowest and highest percentages of initial and secondary abscission of flowers belonged to pollination by GA (13.11-21.44 %) and open pollination (18.33-42.11%), respectively. In addition, the highest initial (54.44) and final (27.66) fruit sets per cluster, the lowest blank nuts (18.01%), and non-split nuts (17.62%) were achieved using pollination with GA. Therefore, it can be concluded that GA is the best male tree for pollination. Akbari cultivar showed the highest nut dry weight per cluster (34.81 g) and the lowest (14.53%) percentage of blank nuts. Manuscript profile