Cell-free translation of the RNA of encephalomyocarditis virus was examined after hybridization of chemically synthesized cDNA fragments to different sites of the 5' noncoding region of the viral RNA. The following results were obtained. (i) The binding of cDNA fragments to the first 41 nucleotides, to the poly(C) tract (between nucleotides 149 and 263), and to the sequence between nucleotides 309 and 338 did not affect translation of the viral RNA; (ii) the binding of cDNA fragments to the sequence between nucleotides 420 and 449 caused a slight inhibition; and (iii) the binding of fragments to eight different sites between nucleotides 450 and the initiator AUG codon (nucleotide 834) caused high degrees of inhibition. The results suggest that the first part of the 5' untranslated region, at least to nucleotide 338, may not be required for encephalomyocarditis viral RNA translation; however, the region near nucleotide 450 is important for translation of the viral RNA. The possibility that initiation occurs at an internal site is discussed.