The order of Rhododendro-Quercetalia mongolicae representing temperate oak forests in Korea was characterized in terms of presence of taxa of different rank. 140 releves were analysed for percentage contribution of each species, genera and families in syntaxa under consideration as well as extracton of diagnostic genera and families for syntaxa by an ordination technique. The Rhododendro-Quercetalia is characterized by high diversity of tree and shrub species contributing 40% of the total floristic composition as well as by a high contribution of the genus Rhododendron and the absence of the genus Fagus, characteristic of the QuercoFagetea sensu lato. The character families for the Rhododendron and Quercus include Liliaceae and Compositae, whereas Acer, Carex, Viola, Rhododendron and Quercus are the most common among genera. Rhododendron and Quercus are regarded as the transgressive cheractergenera, whereas the families of Pinaceae and Ericaceae are considered companions (in sense of the terminology of the Braun-Blanquet syntaxonomy) for the order. Family appeared to be an inadequate rank for diagnoses of alliances and suballiances. On the other hand, genus was found to be the most effective rank in differentiating the alliances and suballiances. The Lindero-Quercenion shares the same character-genera with the order Rhododendro-Quercetalia. Character genera of the suballiances Callicarpo-quercenion are Carpinus, Styrax, Smilax and Callicarpa, and those of the Pino-Quercion list Euonymus, Saussurea and Tilia.