Nucleotide sequences are the fundamental basis for work on molecular mechanisms and for phylogenetic analysis. Recently, we identified sequence errors in all of the LTR sequences of the prototypic foamy virus stored in the GenBank database. Here, we report the resequencing of the proviral plasmids pHSRV13 and pHSRV2. Sequence comparisons revealed an error rate for the foamy virus sequences stored in the database of up to 10 errors per 1000 bp. Even the newest sequences of the codon-optimized foamy virus synthetic Gag, Pol, and Env amino acid sequences showed exchanges compared to the new proviral pHSRV13n sequence. Our results provide evidence that some prototypic foamy virus sequences contain errors and should be revised.