Taxonomic studies were performed on three strains isolated from Cheonho reservoir in Cheonan, Korea. The isolates were Gram-negative, aerobic, rod-shaped, non-motile, catalase-positive, and oxidase-positive. Colonies on solid media were cream-yellow, smooth, shiny, and circular. Phylogenetic analysis of the 16S rRNA gene sequences revealed that these strains belong to the genus Flavobacterium. The strains shared 98.6-99.4% sequence similarity with each other and showed less than 97% similarity with members of the genus Flavobacterium with validly published names. The DNA-DNA hybridization results confirmed the separate genomic status of strains ARSA-42(T), ARSA-103(T), and ARSA-108(T). The isolates contained menaqui-none-6 as the predominant menaquinone and iso-C(15:0), iso-C(15:0) 3-OH, iso-Ci(15:1) G, and iso-C(16:0) 3-OH as the major fatty acids. The genomic DNA G+C content of the isolates were 31.4-33.2 mol%. According to the phenotypic and genotypic data, these organisms are classified as representative of three novel species in the genus Flavobacterium, and the name Flavobacterium koreense sp. nov. (strain ARSA-42(T) =KCTC 23182(T) =JCM 17066(T) =KACC 14969(T)), Flavobacterium chungnamense sp. nov. (strain ARSA-103(T) =KCTC 23183(T) =JCM 17068(T) =KACC 14971(T)), and Flavobacterium cheonanense sp. nov. (strain ARSA-108(T) =KCTC 23184(T) =JCM 17069(T) =KACC 14972) are proposed.