This experiment was conducted to study the effects of glutathione (GSH) on growth performance and growth hormone/insulinlike growth factorⅠaxis in fattening sheep. Twelve sheep aged at three months were randomly allocated into three groups: control (basal diets), treatments 1 (basal diets supplemented with 500 mg/kg GSH) and 2 (basal diets supplemented with 800 mg/kg GSH), with 4 replicates in each treatment. The trial lasted for 60 days. Effects of dietary supplementation of GSH on growth, GH and IGF-Ⅰlevels in serum and IGF-Ⅰ mRNA expression in tissues of fattening sheep were studied. The results showed that the average daily gain (ADG) and the ratio of feed to gain (F/G) was decreased significantly (P＜0.05) for sheep supplemented with GSH, and there were no significant differences about average daily feed intake (ADFI) (P＞0.05) in all groups. The serum GH and IGF-Ⅰlevels of sheep in all GSH groups were significantly higher than those in control group (P＜0.05) at trial period 20, 40 and 60 d. Compared with control group, IGF-Ⅰ mRNA expression in liver and muscle of sheep in all GSH groups were increased, and IGF-Ⅰ mRNA expression in muscle of treatment 2 was increased significantly (P＜0.05). These results indicated that dietary GSH supplementation in diets could stimulate the secretion of IGF-Ⅰ in liver and the expression of IGF-Ⅰ mRNA in muscles, increase the serum GH and IGF-Ⅰ levels, and thereby promote the growth of fattening sheep.