The method of the hazelnut cultivars studying by the morphological indicators of the leaf blade is presented. The method is based on the size of the leaf blade and leaf petiole and general form of leaf blade, a form of the top, base, and distinctness of teeth. The differences and similarities were detected for certain hazelnut cultivars of URIFFM’s selection on the morphological characteristics of leaves. Leaf petiole length is more variable than the leaf size. There are cultivars with either elongated, rounded or wide-rounded leaves. A paired comparison of 12 cultivars according to 8 characteristics showed that the degrees of similarity and differences of cultivars are different. The ‘Klinovidniy’ and ‘Pirojok’ cultivars have the greatest similarity in morphological features of all indicators of leaf blades. They differ only in the form of the top and, to a small extent, in the form of the base of the leaf. The ‘Lozovsky sharovidniy’ and ‘Olympiysky’, ‘Olympiysky’and ‘Serebrisry ’, and ‘Serebristy’and‘ Veleten’ varieties, on the contrary, differ in all characteristics. In general, distinctive features prevail, which indicates the possibility of using the presented methodology for characterizing and identifying cultivars.