This study was conducted to investigate the effects of nutrient restriction on the antioxidant capacity of plasma and gut epithelial tissues in weanling lambs. Forty-eight weanling lambs at the age of 28-day-old were allotted to four groups according to a randomized block design, with four replicates in each group and three lambs in each replicate. The four groups were control group, 40% energy restriction group, 40% protein restriction group and 40% energy+40% protein restriction group, respectively. The experiment lasted for 16 weeks (7 weeks for nutrient restriction and 9 weeks for nutrient recovery). The results showed as follows: energy restriction or protein restriction significantly decreased plasma glutathione reductase (GR) activity and total antioxidant capacity (T-AOC) on the 21st day (P<0.05), and significantly increased plasma malondialdehyde (MDA) content on the 21st day (P<0.05), moreover, the protein restriction significantly increased plasma MDA content on the 41st day (P<0.05); both energy and protein restriction significantly decreased plasma catalase (CAT) and GR activities on the 21st day, plasma CAT and superoxide dismutase (SOD) activities on the 41st day, and plasma T-AOC on the 21st, 41st and 111th day (P<0.05), but significantly increased plasma MDA content on the 21st and 41st day (P<0.05). On the 42nd day of the experiment, the energy restriction significantly decreased glutathione (GSH) content of rumen epithelium and jejunal mucosa, and CAT and GR activities of jejunal mucosa (P<0.05); the protein restriction significantly decreased GSH content of rumen epithelium and jejunal mucosa, and glutathione peroxidase (GSH-Px) activity and T-AOC of jejunal mucosa (P<0.05); both energy and protein restriction significantly decreased GSH content and CAT activity of rumen epithelium and jejunal mucosa, and SOD, GSH-Px and GR activities and T-AOC of jejunal mucosa (P<0.05). On the 112th day of the experiment, the energy restriction significantly decreased SOD activity and T-AOC of jejunal mucosa (P<0.05); the protein restriction significantly decreased T-AOC of rumen epithelium and jejunal mucosa, and SOD activity of jejunal mucosa (P<0.05); both energy and protein restriction significantly decreased T-AOC of rumen epithelium and jejunal mucosa, GSH content of jejunal mucosa, and SOD and GR activities of jejunal mucosa (P<0.05). These results indicate that the antioxidant capacity of plasma and gut epithelial tissues in weanling lambs is damaged by undergoing energy restriction, protein restriction or both energy and protein restriction, and the effects in restricted groups are not absolutely recovered after removing nutrient restriction within trial observation period. ［Chinese Journal of Animal Nutrition, 2010，22（5）:1320-1327］