This study was conducted to determine the effects of glutamine (Gln) supplementation on growth performance, serum hormone levels and small intestinal mucosal enzyme activities of neonatal piglets. Thirty-six 4-day-old neonatal piglets were divided into 3 groups containing 4 replicates of 3 piglets (2 males and 1 female). Piglets in 3 groups were fed basal diet with supplementation of 0 (control group), 0.5% and 1.0% Gln, respectively. The experiment lasted for 18 d. The results showed as follows: compared with control group, dietary supplementation with 1.0% Gln increased average daily feed intake of piglets at 4～14 d of age (P<0.05). Diet supplemented with 0.5% Gln significantly increased the concentrations of serum gastrin of piglets at 14 d of age (P<0.05); supplementation with 1.0% Gln also significantly increased the concentrations of gastrin in serum at 21 d of age in piglets (P<0.05). At 21 d of age, diet supplemented with 0.5% and 1.0% Gln significantly increased the activities of ornithine decarboxylase, Ca2+,Mg2+-ATPase and Na+,K+-ATPase in jejunal mucosal (P<0.05); supplementation with 1.0% Gln significantly decreased the activities of glutamine synthetase and ornithine aminotransferase (P<0.05). Supplementation with 1.0% Gln significantly increased the activities of sucrase, maltase and lactase in jejunal mucosal of piglets at 14 d of age (P<0.05). In conclusion, dietary supplementation with 1.0% Gln could increase intestinal ability to digest in artificial reared neonatal piglets at 14 d of age, and improve metabolism related enzyme activities with Gln in jejunal mucosal at 21 d of age.［Chinese Journal of Animal Nutrition, 2010，22（1）:125-131］