The RNA of American hop latent virus (AHLV) has a molecular size of 7.7 kb measured in agarose gels. Translation products of AHLV RNA in rabbit reticulocyte and wheat-germ cell-free systems ranged in size up to 200 kD. Time-course experiments indicated that a 36 kD peptide, immunoprecipitated by antivirion sera, was synthesized early followed by the sequential appearance of peptides of increasing Mr. An excess of the amino-acid analogue L-canavanine for arginine specifically reduced the quantity of the 36 kD peptide and induced synthesis of a 38-kD peptide in both rabbit reticulocyte and wheat germ. Translation products were not altered by the addition of a reducing agent, and no product appeared to be produced due to limitation of tRNA species or by readthrough. Synthesis of AHLV RNA-directed peptides was blocked by the cap analogue m7G5'ppp5'G, suggesting the presence of a cap structure at the 5' terminus.