Abstract: The Cationic Amino acid Transporter CAT3 (HGMW-approved gene symbol SLC7A3; solute carrier family 7, member 3) plays a crucial role in amino acid nutrition. In this study, researchers cloned and sequenced porcine CAT3 and examined its expression in the porcine small intestine. A 2276 bp porcine CAT3 cDNA fragment was obtained that includes a 127 bp 5'UTR, 1860 bp Open Reading Frame (ORF) and 289 bp 3'UTR. The predicted porcine CAT3 has 619 amino acids with a molecular weight of 66.88 kDa and is 92.4, 94.5, 89.7 and 89.8% identical in amino acid sequence to human, cattle, mouse and rat CAT3, respectively. Real-time RT-PCR analysis showed that porcine CAT3 transcripts are expressed across a panel of tissues of Landrace pigs at the age of day 7 with the highest expression in the brain and heart and moderate expression in the liver, kidney, muscle, intestinal tract and lung. The CAT3 mRNA abundance was significantly higher at day 1 than at other ages in the duodenum and colon (p<0.05) however, it was highest at day 30 in the jejunum (p<0.05) and ileum. There was no significant difference in the CAT3 mRNA abundance in either the duodenum or the jejunum between Landrace and Lantang pigs (p>0.05). The CAT3 mRNA abundance in the ileum of Lantang pigs was significantly higher than that in the ileum of Landrace pigs at day 30 (p<0.05) however, the colon of Landrace pigs demonstrated significantly higher CAT3 mRNA than that of Lantang pigs at day 1 (p<0.05).