The concept and current results of setting up the forest monitoring network at the Kostomukshska Strict Nature Reserve (Zapovednik) are presented. It has been demonstrated that pine forests predominate in the reserve’s forest cover (80.4 % of the forested area), followed by spruce (19.1 %) and birch (0.5 %). The ecological spectrum of the reserve’s forests comprises 7 groups of forest types, with the bilberry group prevailing (67 %) both among pine and among spruce stands. In terms of age structure, coniferous stands in the reserve are even-aged, multi-aged and all-aged, representing stages of the post-catastrophic regeneration succession and phases of subclimax and climax community cycles. Analysis of spatial patterns in the distribution of pristine and secondary forests has shown that anthropogenically altered forests are mainly situated in the western part of the reserve, at the border with Finland. The eastern part is a concentration of pristine north-taiga forests with a distinct mosaic of natural age dynamics phases. It was suggested that the forest monitoring network should be based on the landscape typological and spatial-temporal approaches taking into account the sublandscape-level structure of the reserve’s natural territorial complex and the distribution of forests in the study area by the rate of anthropogenic influence, prevalent species, forest types, and age structure types. Permanent sample plots will be established within 3 model areas (sites). For each of the 5 forest types of pine and 2 types of spruce stands, such plots should represent all age groups of even-aged stands (4 sample plots at maximum), and at least one sample plot should be allocated for each type (subtype) of the uneven-aged structure. The preliminary estimate is that, in total, there should be at least 98 permanent sample plots in the forest monitoring network of the Kostomukshskiy Zapovednik. So many units are needed to work out the algorithm for correcting the existing forest compartment characteristics given by the forest inventory in what concerns the age structure and the succession phase of stands. It is foreseen that all the factual material thus amassed will serve as the basis for modeling the scenarios of the natural dynamics of this forest massif and, perhaps, of other objects with similar structure. For citation: Raevsky B.V., Ilinov A.A., Medvedeva M.V., Rudkovskaya O.V. The Natural Dynamics Monitoring System of the Forests in the Kostomukshsky Reserve. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 6, pp. 81–101. (In Russ.). https://doi.org/10.37482/0536-1036-2023-6-81-101