The genomic RNA of apple chlorotic leaf spot virus was translated in a rabbit reticulocyte lysate system, yielding a large, 190 K product as well as several other polypeptides of smaller size (60, 56, 22 and 15 kDa). The 22 kDa product was immunoprecipitated by an anti-ACLSV serum and comigrated with purified ACLSV coat protein. In vitro translation of RNA transcripts prepared from cloned ACLSV cDNAs demonstrates that the coat protein is synthesised by initiation on the second in frame AUG codon of the 28 kDa open reading frame located at the 3' end of the genome. In the in vitro translation system used, the ability of various ACLSV-derived RNAs to direct the synthesis of the coat protein appears to be the result of initiation on the internal AUG codon.