Genetic variations in Ranunculus cantoniensis DC, were examined through nucleotide sequence of ITS regions on five Korean and Japanese populations and compared with previous karyological research and RAPD analysis results. All examined individuals had 648 base pairs in their ITS regions. The lengths of ITS-1 and ITS-2 were 254 bp and 264 bp, respectively and 5.8S was 130 bp. Twenty sites were variable and fifteen sites were genetically informative. They were clearly separated into two groups by neighbor-joining tree. One group coincided with the Atsuki group and the other with the Matsuyama group of karyological classification. Variations of nucleotide sequence analyses were very useful in illustrating intraspecific genetic differentiation of R. cantoniensis.