Two strains, designated B1-1(T) and B6-8(T), were isolated from the Geumho River and the Dalseo Stream in Korea. Comparative 16S rRNA gene sequence analysis showed a clear affiliation of these two bacteria with the class Alphaproteobacteria, their closest relatives being Kaistia adipata KCTC 12095(T), Kaistia granuli KCTC 12575(T), Kaistia soli KACC 12605(T) and Kaistia terrae KACC 12910(T) with 16S rRNA gene sequence similarities of 95.3 -97.7 % to the two novel strains. Strains B1-1(T) and B6-8(T) shared a 16S rRNA gene sequence similarity value of 96.1 %. Cells of the two strains were Gram-reaction-negative, aerobic, non-motile, short rods or cocci. The predominant ubiquinone was Q-10. The major fatty acids were C(16 : 0,) C(18 : 1)ω7c, C(18 : 0) and C(19 : 0)ω8c cyclo for strain B1-1(T) and C(16 : 0,) C(18 : 1)ω7c, C(18 : 0), C(18 : 1) 2-OH, and C(19 : 0)ω8c cyclo for strain B6-8(T). The G+C contents of the genomic DNA of the strains B1-1(T) and B6-8(T) were 61.6 and 66.5 mol%, respectively. Based on the results of this polyphasic study, strains B1-1(T) ( = KCTC 12849(T) = DSM 18799(T)) and B6-8(T) ( = KCTC 12850(T) = DSM 18800(T)) represent two novel species of the genus Kaistia, for which the names Kaistia geumhonensis sp. nov. and Kaistia dalseonensis sp. nov. are proposed, respectively.