To clarify the key characteristics of Korean brown frogs (R. dybowskii, R. huanrenesis and R. amurensis coreana), this study employed a morphological and morphometrical comparisons among brown frogs found in Korea and Japanese endemic species, R. tsushimensis. As a result, it was considered that the key characteristics were the shape of the finger and toe tips, the markings of the lower jaw, the presence or absence of an upper lip line, the development of toe webbing, and the shape of the vomerine teeth series by morphological comparisons of brown frogs. Also, there were significant differences in tympanum diameters and foot lengths of the four species of brown frogs. Therefore, a comparison between morphological and morphometric characters is an effective way to clarify the identification of brown frogs.