Genetic diversity of coxsackie A viruses (CAVs) and enteroviruses 68, 69, and 71 was studied by comparing nucleotide and derived amino acid sequences from the 5' untranslated region (5'UTR), VP4-VP2 capsid protein and polymerase 3D region, and 3'UTR. The data were obtained by sequencing PCR amplicons. According to the molecular analysis of the coding region, CAVs belong to three different genetic clusters. CAV2, 3, 5, 7, 8, 10, 12, 14, and 16 form a coherent genetic group designated cluster A. No other enteroviruses, apart from enterovirus 71, are found in this cluster. CAV9 is the only member of the subgroup found in the same genetic group with coxsackie B viruses, the major group of echoviruses and enterovirus 69 (cluster B). Cluster C includes CAV1, 11, 13, 15, 17, 18, 19, 20, 21, 22, and 24 which are genetically close relatives of polioviruses. Enterovirus 68 is related to enterovirus 70 (cluster D). Clusters different from those in the coding region are found in the 5'UTR while the grouping in the 3'UTR is similar to that found in the capsid region. Correlation of these findings with evolution, pathogenesis, and classification is discussed.