Expression of the pol gene of the murine leukemia viruses is subject to translational control at the UAG termination codon of the upstream gene gag. Previous experiments have suggested that: i) Moloney murine leukemia virus infection induces a tRNA(Gln)iii) in an in vitro system using the tobacco mosaic virus as template, this tRNA is able to increase readthrough at the UAG codon [1]. Here we demonstrate that, in vivo, Moloney murine leukemia virus infection does not increase translational readthrough at either the tobacco mosaic virus or the Moloney murine leukemia virus UAG stop codons.