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 menaquinone-6 as the predominant menaquinone and iso-$C_{15:0}$, iso-$C_{15:0}$ 3-OH, iso-$C_{15:1}$ 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 $14972^T$) are proposed.