Many sequences of hepatitis C virus (HCV) have been reported, but there has been no report about the evolutionary classification of HCV. The aim of this study is to classify the nucleotide sequences of HCV into appropriate genetical groups by molecular evolutionary methods. A number of nucleotide sequences of HCV were collected from all over the world. First, all HCV nucleotide sequences for each region were aligned to optimize homologies. Phylogenetic trees were then constructed for each region of HCV according to the number of the nucleotide substitutions. HCVs can be classified into two or three major groups in the trees of each regions. However, minor groups can be classified into two in that of 5' non-coding, four in that of Core, Env., E2/NS1, NS3 and NS4 region and six in that of NS5 region. However, the full sequences such as HCV-1, HCVH and HCV-J4, were always located in the same major and minor groups in that trees of all regions. These data indicated that HCVs can be classified into two or three major and six minor groups.