Stone-birch (Betula ermanii) forests were studied at the northern limit of their range in the north of the Koryaksky District. The species composition, community structure, and habitats of stone-birch groves are described. Their altitudinal position and geographical distribution are discussed. A classification of stone-birch communities on Olyutorsky Gulf coast was developed using the dominant-determinant approach. Within the study area, the community diversity of stone-birch forests was represented by 5 associationsforming 3 groups of associations: Betuleta pteridosa (fern-rich stone-birch forests), Betuleta calamagrostidosa (grass-rich stone-birch forests), and Betuleta fruticosa (shrub-rich stone-birch forests). All the syntaxa have been previously described from the Kamchatka Peninsula. The Koryak communities differed from their Kamchatka analogues in the floristic composition, lower species diversity, and high density of the shrub layer. The most important characteristics of shrub-rich stone-birch communities were the high abundance of Sorbus sambucifolia and Alnus fruticosa, while for fern-rich communities it was the predominance of Dryopteris expansa in the herb layer. The intrazonal stone-birch groves are considered to be the remnants of widespread birch forests of the Holocene climate optimum, which ended ca. 5 Ka B. P. They have survived on the southern maritime slopes of the Koryak Upland ridges and turned into fragmentary and floristically impoverished communities. The relic stone-birch groves of the Koryak Upland are regarded as rare and endangered communities in need of special protection.