The Turkish forests are a complex of Mediterranean, European, Euxine and Irano-Turanian influences. The boundaries between these 4 bioclimatic-biogeographical zones have, especially in the E of the country, been little studied and their limits are difficult to establish. Phytosociological and biogeographical aspects of these forest zones are discussed. In the bioclimatic-Mediterranean region, the forest and pre-forest structures are related to QUERCETALIA ILICIS in the thermo- and meso-Mediterranean stages, and to QUERCETALIA PUBESCENTIS in the supra-Mediterranean stage, except in southern Anatolia where they belong to QUERCO-CEDRETALIA LIBANI. In the prepontic bioclimatic region where the Mediterranean influence is still perceptible, they belong to QUERCO-CARPINETALIA ORIENTALIS and in the Euxine bioclimatic region to RHODODENDRO-FAGETALIA ORIENTALI and to PINOPICEETALIA ORIENTALIS. Some forest formations in NW Anatolia, with a European mountain influence, are related to FAGETALIA SYLVATICAE and to VACCINIO PICEETALIA.