Peroxiredoxin (Prx) is an antioxidant protein, which protects organisms against various oxidative stresses. In this study, we isolated Peroxiredoxin cDNA from the muscle tissues of American white shrimp, Litopenaeus vannamei, using reverse transcription-polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE). The full-length cDNA consists of 962-bp, which includes a 49-bp 5′-untranslated region (UTR), a 316-bp 3′-untranslated region, and a 597-bp open reading frame (ORF) encoding 198 amino acids. The signal peptide sequence was not found in this cDNA. We aligned the deduced amino acid sequence with the known amino acid sequences of Fenneropenaeus indicus, Fenneropenaeus chinensis, Marsupenaeus japonicus, Scylla serrata, Drosophila melanogaster, Bos taurus, Branchiostoma belcheri, Anoplopoma fimbria, and Rattus norvegicus, and the sequence similarities scores were found to be 97%, 96%, 95%, 83%, 72%, 70%, 80%, 81%, and 75%, respectively. We also found 2-cysteine (Cys) residues in this peroxiredoxin sequence. The RT-PCR analysis revealed that the peroxiredoxin mRNA was expressed in the gills, hepatopancreas, muscles, intestine, and hemocytes. Studies using this newly cloned peroxiredoxin gene from Litopenaeus vannamei will add to the existing knowledge base on the physiological role of peroxiredoxin in shrimp species.