The downstream 5' nontranslated regions of seven echoviruses with different neurovirulent phenotypes were amplified and sequenced. Neurovirulent echovirus serotypes 4, 6, 9, 11, and 30 were identical to the putative poliovirus in 18S rRNA binding sequence and the flanking conserved sequences. Less neurovirulent echoviruses, serotypes 2 and 12, exhibited variations within these regions.