Nucleotide sequences of the genome of enterovirus 70(EV70) isolated in Osaka in 1993 were determined, and compared with those of the past epidemic strains. Nucleotide substitution rates in 332 bp, 174 bp, and 178by of the genes encoding viral protein (VP)1, VP2, or VP3 were 9.0, 7.5, and5.6% between Kumoi-2/93 andJ670/71, respectively. Likewise, the putative amino acid substitution rates were 1.8, 0, and 0%. It seems that the epidemic strains ofEV70 in Japan have been evolving at a constant high nucleotide substitution rate but almost all the substitutions were synonymous.