Abstract: This study was undertaken to investigate the effects of dietary nucleotides on growth performance,body composition,tissue biochemical composition and non--specific immunity of juvenile shrimp(Litopenaeus vannamei).960 shrimp(0.43?0.01) g were randomly allocated into 8 groups.The control group was fed with the basal diet,while the other seven groups were fed with the basal diet added with 0.1,0.2,0.4,0.6,0.8,1.0 and 1.2 g/kg mixture of adenosine-5′-monophosphate(AMP),cytidine-5′--monophosphate(CMP),uridine-5′-mono-phosphate disodium salt(UMP),inosine-5′-monophosphate disodium salt(IMP)and guanosine-5′-monophosphate disodium salt(GMP)(1∶1∶1∶1∶1 W/W,mix-NT)respectively.After 5 weeks feeding,the results showed that weight gain rate(WGR),specific growth rate(SGR)and feed intake(FI)in shrimp fed 0.4 g/kg mix-NT were significantly higher than those in the control group(P<0.05).Protein deposit rate(PDR)in 0.6 and 1.0 g/kg groups increased significantly compared with the control group.No significant difference was found among all the treatments in feed conversion rate(FCR),survival rate(SR)and hepatosomatic index(HSI)(P>0.05).The crude lipid and ash content were significantly affected by the dietary mix-NT levels(P<0.05),while the dry matter and protein content showed no significant difference(P>0.05).RNA content in hepatopancreas increased significantly(P<0.05)with dietary mix-NT increasing,TP content was not significantly affected(P>0.05).TP and RNA content in intestine increased significantly with dietary nucleotides increasing(P<0.05).The uric acid(UA)content in serum decreased significantly in 0.6 g/kg group and glutamic-oxalacetic transaminease(GOT)activity increased significantly in 1.2 g/kg group(P<0.05).Dietary mix-NT significantly increased PO activity in gill,lysozyme(LZM)activity in hepatopancreas and serum(P<0.05).However no significant difference was observed in all the trial groups in glutamic-pyruvic transaminase(GPT)activity,high-density lipoprotein(HDL)content and muscle PO activity(P>0.05).In conclusion,dietary mix-NT could improve growth performance and nutrition metabolism,raise total TP and RNA content in hepatopancrea and intestine,and enhance non-specific immunity of juvenile L.vannamei.