Abstract: RNA transcripts from Spe-1 linearised PMTV-T RNA 3 cDNA clone were translated in wheat germ extract system. Two major translation products of 19.7K and 65K correspond to the predicted translation products of RNA 3: 19.7K produced by coat protein and 65K by read-through of translation termination codon. The mean density of the coat protein band was 3.253 as determined by Whole Band analysis of different exposures of autoradiographs. Similarly, the mean density of the boat protein plus read-through protein band was 0.209. This gives a ratio of 0.064 for the density of the coat protein plus read-through protein: coat protein. However, there are three methionine residues in the coat protein and 8 in the coat protein plus read-through protein. Normalising for this gives a ratio of 0.024 for amount of coat protein plus read-through protein: coat protein. In other words -2.4 percent of the ribosomes which reach the coat protein gene termination codon suppress the termination and go on to produce coat protein plus read-through protein.