Evaluation of the influence of Reglalg biostimulator and microelements on the peroxidase and polyphenol oxidase activity in pears leaves. The scientific research were performed on the pears trees of the late Noiabrscaia variety, grown in the lysimeters of the plant complex of the institute. The pears trees were treated foliar with the biostimulator Reglalg solution (0.05%) and the microelements B, ZN, Mn, Mo (0.1%), after 10-12 days from flowering and in the phase of intensive growth of shoots. For analysis, leaves were taken every two weeks (June - August), selected from trees treated during the vegetation period according to the variants Reglalg, Reglalg + microelements and water-treated trees served as controls. The activity of the enzymes peroxidase (PO) and polyphenoloxidase (PFO) was determined after the methods (Ermacov, 1987 and Voscresenscaia, 2006). During the vegetation period, there was a gradual increase in the activity of PO and PFO enzymes, having the highest values in early August. During this month, the activity of the OP decreased and the PFO remained unchanged. The change in the activity of these enzymes during the growing season depended on the intensity of the metabolic and physiological processes that took place in certain phenophases as the activity of these enzymes increased and greatly influenced the drought in August. In the treated variants, the activity of these enzymes was much higher than in the control variant. These substances have had a beneficial effect in regulating the activity of PO and PFO enzymes that play an important role in the vital processes, in the resistance and plant productivity. With the modification of the activity of these enzymes during the phenophases we find their participation in metabolic processes in the development of plants in ontogenesis, which correlates with the functions of resistance and adaptation of plants to adverse environmental conditions and consequently productivity formation and fruit quality. The activity of peroxidase as well as of the polyphenol oxidase in the pears leaves of Noiabrscaia depended on the biological peculiarities of the variety, the environmental conditions, the metabolic processes from certain phenophases and on the substances with which the pears trees were treated. The biostimulator Reglalg and Reglalg + microelements influenced more the increase of the peroxidase and polyphenol oxidase activity in the leaves compared to the control variant.