Glutathione (GSH) serves as a major endogenous antioxidant and its kinetics have been poorly described in the weaned pig. This study was to assess the effect of birth weight, sex, and days postweaning on the small intestine (SI) mucosal GSH kinetics. At weaning (18.8 ± 0.44 d) 34 pairs of intrauterine growth restricted (IUGR) and normal birth weight sex-matched littermates were selected and fed a starter diet ad libitum until 1 h before sampling at 0, 2, 5, 12 and 28 d postweaning. Mucosa was collected from 2 SI sites, at 5% and at 75% of total length, to determine GSH and glutathione disulfide (GSSG), glutathione peroxidase (GSH-Px) and malondialdehyde (MDA), and plasm GSH-Px and MDA. At both 5 and 75% of total length, the GSH-Px activity and GSH concentrations increased gradually with increasing days postweaning to peak at day 12 (P < 0.05). The GSH-Px activity and GSH concentrations at 5% of SI length were consistently higher as compared to 75% of SI length (e.g., at day 12, 43.2 and 28.9 units/mg protein and 21.5 and 15.4 μmol/g protein, respectively). The GSSG:GSH ratio at 5% of total length was 2-fold higher at day 5 compared to all other days (P < 0.05), possibly indicating that the mucosal redox balance was disturbed in that time window. The higher GSH-Px activity, GSH content, and GSSG:GSH ratio in the proximal SI might illustrate the higher need for antioxidant action at that site. Plasma MDA and GSH-Px activity followed a comparable pattern as in the small intestine.