As a potential mammary gland transport system, oligopeptide transporter 2 (PepT2) plays important role in amino acids nitrogen transportation, drug distribution and diseases therapy. Intensive study on PepT2 is important for lactation physiology and clinical therapy. Protein structure, characteristic of substrate transport, regulation of gene expression and physiological significance of PepT2 were mainly reviewed in this study.［Chinese Journal of Animal Nutrition, ２００9，２1（5）:603-608］