Inter- and intraspecific genetic relationships between Rana amurensis from Korea and Russia and other brown frogs were investigated by nucleotide sequence of a 504 base pair (bp) fragment of the mitochondrial cytochrome b gene. Nucleotide sequence similarities among Korean populations of R. amurensis ranged from 99.6% to 97.6% and 98.8% within Russian populations. The nucleotide sequence similarity between Korean and Russian R. amurensis ranged from 86.9% to 85.5%. Based on Kimura-2-parameter distance, the sequence divergence between R. amurensis from Korea and Russia was 16.18% and 18.04% among other related brown frogs. interspecific sequence divergences among R. amurensis and other related brown frogs diverged by 20.3%. Using an estimate of 2-4% mitochondrial DNA sequence divergence per million years, Korean and Russian R. amurensis diverged about 8 to 4 million years ago (Mya) and other brown frogs diverged about 9 to 5 Mya from ancestral frogs and distributed from North Asia to Sakhalin in a short time. In the neighbor-joining and UPGMA tree R. amurensis was clustered into two groups with Korean and Russian populations and the other brown frogs were grouped separately with diverged trichotomous clusters (R. dybowskii and R. pirica, R. okinavana and R. tsushimensis, and R. japonica and R. longicrus).