The nature conservation significance of 20 associations of birch-pine and pine forests from the Northern and Western Caucasus was assessed using a system of international criteria. The analyzed 6 alliances represent relic communities of various paleo-geographical periods which occur in isolation from their main parts of ranges. Pinus brutia var. pityusa forests of the Jasmino fruticantis–Juniperion excelsae alliance are tertiary relict communities of the Mediterranean type with species richness of 216 and with the presence of 23 Red Data Book species. The Western Caucasian hemi-xerophilous sub-Mediterranean forests of the Campanulo longistylae– Pinion brutiae alliance include 205 plant species, of which 27 are rare and endangered species. The East Caucasian sub-Mediterranian forests of the Onobrychido cornutae–Pinion sylvestris alliance include 98 species, of which 28 are Caucasian endemics and 6 are Red Data Book species. The European-Siberian hemiboreal forests of the Bupleuro polyphylli–Pinion sylvestris alliance are relict Pleistocene communities containing 244 plant species and 16 Red Data Book species. Hemiboreal forests of the Asyneumo–Pinion sylvestris alliance contain 243 plant species, of which 96 are endemics and 10 are Red Data Book species. An analysis of threatened factors and current conservation status has been carried out for all types of forests.