Several mammalian thioredoxin cDNA sequences, namely that of human, macaca, ovine, bovine, equine and murine have been already registered in the Genbank database; but that of porcine is still not known. In this communication, we report the full-length cDNA sequence of porcine thioredoxin as determined by RT-PCR method. We also compared the protein sequence of thioredoxin from various mammals. Multialignment of the amino acid sequences between porcine and other mammalian species revealed that the sequences are highly conserved. Only one difference exists between the amino acid sequences of porcine and bovine thioredoxin.