In order to evaluate the effect of saponin,extracted from Quillaja saponaria,on non-specific immunity of turbot Scophthalmus maximus,fish was immersed in seawater containing saponin at concentration of 0,15 and 35 mg/L respectively for 1 h.No-specific immune parameters including leukocytes phagocytic activity,ACH50 and total protein of serum,activiies of lysozyme,antibacterial and AKP in serum and skin mucus were analyzed 6,12,24,48 and 72 h after the treatment.The results show that the leukocyte phagocytic activity in the lower concentration group(15 mg/L)at 12 h and in the higher concentration group(35 mg/L)at 24 h was significantly higher than that in the control group(P<0.05).ACH50 in two treatment groups at each testing time were significantly higher than that in control group except the ACH50 in the lower concentration group at 12 h and 24 h(P<0.05).The highest lysozyme activities in serum appeared in the lower concentration group at 6 h,but no ACH50 could be detected in skin mucus.Antibacterial activity in each group changed with time,but it was improved obviously in the two treatment groups at 6 h and 12 h after the immersion,also no difference between the higher and lower saponin groups(P>0.05).Antibacterial activity in serum was too low to be detected.AKP activity of serum in two treatment groups was significantly higher than that in the control at 6 and 12 h respectively(P<0.05),furthermore,obvious differences were found between the two treatment groups.AKP activity of skin mucus in two treatment groups was significantly higher than that in the control at 12 h(P<0.05),but no differences were found between the two treatment groups(P>0.05).Serum total protein in higher concentration group reached the highest value at 6 h,then came to the same level with low concentration group and control group at 12 h.From 24 to 72 h,serum total protein in higher concentration group was remarkably higher than that in the lower concentration and control group.The results indicate that saponin could enhance the non-specific immunity of turbot.