We found a brown frog species, which is unrecorded from South Korea. Rana huanrenensis Fei, Ye, and Huang (1990), This species was originally described from northeastern China. In having 2n=24 chromosomes, this species is closely related to Rana dybowskii, R. chensinensis, R. ornativentris, R. pirica, and Chinese R. huanrenensis, but it is different from the first four species in the ecological, morphological, and genetic characteristics. By contrast, this species Is identical to Chinese R. huanrenensis In the habitat of montane stream-breeding, absence of the vocal sac, and genetic properties. This record is a significant range extention of R. huanrenensis.