This study was designed to determine the effects of dietary inositol on immune function of juvenile Wuchang bream(Megalobrama amblycephala)under ammonia stress.In trial,four hundred and fifty juvenile Wuchang bream with initial body weight of(3.40±0.07)g were randomly allocated to 6 groups(with 3 replicates)fed with purified diet containing inositol 0,101.2,202.3,404.8,809.1 and 1 616.4 mg/kg for 90 days.The results showed that,before ammonia stress,compared to the control group,Lym,C3,C4 and respiratory burst activity of fish fed diet 404.8 mg/kg inositol were significantly higher(P<0.05).Under ammonia stress for 12 hours,the WBC,RBC,Lym,HGB,C3 and C4 were significantly higher in the groups supplemented with 404.8 and 809.1 mg/kg inositol(P<0.05);respiratory burst activity was significantly higher than that of control(P<0.05);cortisol level was significantly decreased(P<0.05).Under ammonia stress for 72 hours,the WBC,RBC,Lym,HGB,C3 and respiratory burst activity fed diet 404.8 mg/kg inositol were significantly higher(P<0.05);cortisol level was significantly decreased(P<0.05);C4 levels was was significantly enhanced in the group supplemented with 809.1 mg/kg inositol(P<0.05).So,it is suggested that ingestion of a basal diet supplemented with inositol(404.8 mg/kg)can enhance immune function and resistance against ammonia stress of juvenile Wuchang bream.