Abstract: Objective To investigate the effect of different concentration of total astragalus saponin on the growth of tumor cells and immune function in H₂₂-bearing mice.Methods The H₂₂ liver tumor model was established and the H₂₂-bearing mice were randomly divided into a tumor bearing model group,low-,medium-,and high-dose total astragalus saponin treatment groups;a control group was also set.At the end of 10 day's treatment,tumor inhibition ratio,spleen index,and thymus index of all the mice were determined with weighing method;multiplication capacity of lymphocytes and the transformation ability of T lymphocytes were tested with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay;meanwhile,interleukin-2 (IL-2) content was detected with enzyme-linked immunosorbent assay (ELISA).Results Compared with those in the control group,the body weight (24.90±2.82 g),thymus index (1.47±0.45 mg/g),and spleen index (3.97±0.05 mg/g) decreased significantly in the model group (P<0.05 for all); the lymphocyte multiplication capacity (0.10±0.02) and the T lymphocyte transformation ability (1.08±0.03) declined obviously in the model group (both P<0.01);the IL-2 content (87.59±28.60 pg/ml) was significantly down-regulated in the model group (P<0.01).Compared to that in the model group,the growth of tumor in total astragalus saponin treatment groups was obvious inhibited (P<0.01).For the mice of low-,medium-,and high-dose total astragalus saponin treatment groups,the thymus index (2.18±0.34,2.47±0.54,and 2.51±0.46 mg/g),the spleen index (1.14±0.07,6.13±0.71,and 6.46±0.85 mg/g),the capacity of lymphocyte multiplication (0.17±0.01,0.18±0.03,and 0.19±0.01),the lymphocyte transformation (5.42±0.84,1.15±0.06,and 1.20±0.07),and the content of IL-2 (117.67±30.28,121.80±34.04,and 124.93±37.10 pg/ml) were all higher than those of the model group.Conclusion The total astragalus saponin could inhibit the proliferation of tumor cells in H₂₂-bearing mice and the mechanism of the inhibitive effect may be related to increased immune function.