Abstract: To investigate the effect of dietary concentrations of leucine and intrauterine growth retardation( IUGR) on antioxidant function in the liver of weaned piglets. Sixteen normal birth weight( NBW) and sixteen IUGR newborn piglets were selected.All piglets weaned at 14 d of postnatal age and fed either a control diet or a control diet supplemented with 0.35% leucine for 21 days.Therefore,one 2 × 2 factorial experimental design was used and each group had eight replications,with one piglet per replication. Compared with NBW piglets,IUGR piglets had lower total superoxide dismutase( T- SOD) activity whereas increased malondialdehyde( MDA) content in liver( p < 0.05).There were significant decreases in the activities of Mn- superoxide dismutase( Mn- SOD) and glutathione peroxidase( GSH- Px),and the content of glutathione( GSH) in the hepatic mitochondrial of IUGR piglets than those in the NBW piglets( p < 0.05). In addition,IUGR decreased the mRNA expression levels of nuclear transcription factor 2( Nrf2),superoxide dismutase 1( SOD1),superoxide dismutase 2( SOD2) and glutathione peroxidase 1( GPx1) in liver( p < 0.05). Dietary supplementation of 0.35% leucine significantly decreased MDA content but increased SOD2 mRNA abundance in liver( p < 0.05). A higher leucine inclusion alleviated the decreased mitochondrial GSH content and the down- regulated SOD2 and GPx1 mRNA abundances in liver( p < 0.05). Thus,dietary supplementation of 0.35% leucine attenuates the hepatic lipid peroxidation induced by IUGR,which may be associated with the partially improved antioxidant capacity in the liver of piglets.