The nucleotide sequence variations of mitochondrial DNA were investigated by eleven restriction endonucleases from two toad species in South Korea. The two species studied were Asian toads (Bufo bufo) and Water toads (B. stejnegeri) from 5 localities throughout the country. A total of 20 toads (8 for Asian and 12 for Water toads) were analyzed for mtDNA fragments by the restriction enzymes and electrophoresis. An average of 33 mtDNA fragments was obtained for Asian toads from each locality and 35 fragments for Water toads. No size variation of mtDNA was detected within and between two species. The estimation of mtDNA size was approximately 18.3±0.5kb. The degree of mtDNA sequence divergence for B. bufo was 1.13% and that of B. stejnegeri was 0.2%. The amount of sequence divergence between two species was 7.31% which was somewhat lower than the other Korean frogs. The divergence time between two species was estimated to be about 3.5 million years ago.