The gypsy moth, Lymanria dispar, is one of the most widespread pest-insects in the Russian Federation. Anastatus japonicus Ashmead and Ooencyrtus kuvanae Howard are parasites that live on the eggs of L. dispar. They can be found in the European part of Russia, where the insects were imported from North Korea in 1988. The usage of O. kuvanae to limit the gypsy moth populations requires recognition of the release rates and effectiveness in preventing mass pest outbreaks, as well as for the evaluation of the possibility of elimination. An experimental release of O. kuvanae (237 500 specimens) was conducted in 2019 during a gypsy moth outbreak in the Orenburg region, which covered the basin of the Ural River within the territory of three forestries. The average number of clutches of O. kuvanae varied from 1 to 20 clutches per tree. The control of efficiency was made 48–52 after the release, during the incubation period of the 3ed generation of O. kuvanae. The clutches were collected and experimentally analyzed. The release rate of L. dispar ranged 82.9–90.3 % at the locations with a density of 107–268 thousand eggs/ha and did not exceed 47.3 % at the locations with a density of 3800 thousand eggs/ha. A coefficient for estimation of the optimal number of O. kuvanae specimens per 1 ha was proposed based on the proportion of the released egg parasitoids per 1 ha and the absolute number of the destroyed eggs of L. dispar. The regulation of the gypsy moth’s population by O. kuvanae should be done at the biggening of the foci formation. The usage of the entomophage in the active reproductive foci of the gypsy moth, with an infestation rate higher than 1.5 clutches per tree, cannot reduce the phytophage numbers to a harmless level. The application of O. kuvanae can be a part of an integrated system of preventive measures: chemical or biological pesticide treatments to reduce gypsy moth populations, and after initiate the release of the entomophages. For citation: Sergeeva Yu.A., Dolmonego S.O. Application of Ooencyrtus kuvanae Howard Against Gypsy Moth. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 3, pp. 69–83. (In Russ.). https://doi.org/10.37482/0536-1036-2023-3-69-83