Abstract: This study was conducted to investigate the effects of dietary glutathione(GSH)on growth performance,tissue biochemical indexes and non-specific immune related enzymes of GIFT Oreochromis niloticus.720 fish with initial weight of(3.27?0.04)g were randomly allocated into 6 groups.The fish in control group were fed the basal diet(G0),while those in the other five groups were fed the basal diet added with 80,160,240,320,400 mg/kg GSH.After 7 weeks’ feeding,weight gain rate(WGR),specific growth rate(SGR),protein efficiency ratio(PER)and RNA/DNA ratio of liver in 320 mg/kg group were significantly higher than those in the control group(P<0.05),and feed coefficient(FC)was significantly lower(P<0.05).Hepatosomatic index(HSI)was higher in GSH added groups than the control,showing no significant difference(P>0.05).Among all groups,no significant difference was found in condition factor(CF)(P>0.05).The whole-body crude protein content and crude lipid content were significantly affected by dietary GSH levels(P<0.05),while the ash and dry matter content showed no significant difference(P>0.05).Serum UN content was significantly lower in 320 mg/kg group compared with the control(P<0.05).The IGF-Ⅰlevel in G160-G400 mg/kg groups was significantly higher than the control and 80 mg/kg groups.The serum lysozyme(LZM)activities increased significantly in 240,320 and 400 mg/kg groups compared with the others(P<0.05),and liver LZM activities were significantly higher in 320 and 400 mg/kg groups(P<0.05).Dietary GSH increased serum alkaline phosphatase(AKP),phenoloxidase(PO)and liver AKP,acid phosphatase(ACP)activities,but no significant difference was shown(P>0.05).Serum nitric oxide synthase(NOS)activities in 320 mg/kg group were significantly higher than the control(P<0.05),but those in liver showed no significant difference(P>0.05).The result suggested that dietary GSH could significantly improve growth performance,raise whole-body crude protein and crude lipid content,increase serum and liver IGF-Ⅰ level,and enhance activities of non-specific immune related enzymes in GIFTOreochromis niloticus.The optimum level of dietary GSH was 355.13 mg/kg on the basis of WGR.