The present study was undertaken to classify and describe the oak (Quercus spp). forests on Mts. Kaya, Bisul, Unmun and Kaji in southern Kyongpook Province, Korea by using a reciprocal averaging method (RA ordination) and the methodology of the ZM school of phytosociology. A temporary vegetation table was prepared by the RA ordination. The diagnostic species of the Quercus forests derived from the ordination were compared with the characteristic and differential species of the existing phytosociological vegetation units of the other mountainous areas of Korea. As a result, the forest vegetation was classified into the next vegetation units: Fagetea crenatae Miyawaki et al. 1968; Acero-Quercetalia mongolicae Song 1988; Rhododendro-Qurcion mongolicae Song 1988, 1. Stephanandra incisa-Quercus mongolica community 1-1 Sasa borealis subcommunity, 1-2 Disporum smilacinum subcommunity; Lespedezo-Quercion serratae Takeda et al. 1994, 2. Spodiopogon sibiricus-Quercus serrata community. The Rhododendro-Qurcion mongolicae and the Lespedezo-Quercion serratae correspond to the cool-temperate forests of the northern type and the southen type (Honda 1922), respectively, in the Korean Peninsula. Also some phytosociological problems in Korea were discussed here in detail from the floristic viewpoint in the present study.