The biosphere reserve has a cluster structure and is composed of 8 separate massifs; It covers all the altitude belts characteristic for the southern maroslope of the Carpathians: foothill oak forests (180-450 m.a.s.l.), mountain beech and mixed forests (450-1000 m.a.s.l.), mountain spruce forests (1.000-1.450 m.a.s.l.), subalpine meadowsand crooked woodland (1.450-1.800 m.a.s.l.) and alpine meadows (1.800-2.061 m.a.s.l.); 44.100 ha, or over 82 %of the area is forested, and almost 21.000 ha out of it belong to primeval forests, which are now listed in the UNESCO World Natural Heritage List as components of the serial Ukrainian-Slovak transboundary property “Beech Primeval Forests of the Carpathians”; Vegetation of the reserve is represented by about 400 associations, 102 ofwhich are rare ones, listed in the Green Book of Ukraine; Flora of the reserve contains 3.019 species (1.349 highvascular plant species), 114 of which are rare ones, listed in the Red Book of Ukraine and international conservation lists; Fauna of the reserve contains 4.813 species (306 vertebrate species), 232 of which are rare ones, listed in the Red Book of Ukraine and international conservation lists. 3 species of troglobiont insects - Duvalius transcarpaticus (Carabidae, Coleoptera), Willemia virae та Aropalites carpaticus (Collembola) – are distributed exclusively within the karst caves of the reserve; 23 habitats found in the reserve are globally threatened.