When preserving pears, the Noiabriscaia variety under normal atmospheric conditions and by the method of treatment with the synthetic inhibitor of ethylene Fitomag, the modification of peroxidase and polyphenol oxidase activity in fruit depended on the conditions and duration of keeping, on the metabolic processes that took place in fruit and their keeping methods. During the keeping period of pear fruits preserved by both methods in their maturation process simultaneously with the decrease of peroxidase activity there was an increase in polyphenoloxidase activity that confirms the differentiated role of these enzymes in metabolic processes. In pear fruits preserved by the Fitomag method, the activity values of both enzymes were much lower with that storage in the ordinary atmosphere.The lower intensity of the oxidation-reduction processes has beneficially in- fluenced the preservation of the quality of the fruits preserved by this method compared to those preserved in the usual atmosphere. SBA Reglalg and the microelements used in the foliar treatment of trees during the vegetation period had less influence on the activity of these enzymes in pear fruits.