Objective To study the substitutablility of Huangqi （Astragalus membranaceus） and Hongqi （Radix hedysari） in Buzhong Yiqi Decoction （Decoction for reinforcing middle-jiao and replenishing qi） in improving immunologic function in mice. Methods Forty normal Kunming mice were randomized into four groups with 10 in each

i.e. control group

cyclophosphamide model group

BuzhongYiqi Decoction containing Huangqi group （Huang qi group）

and Buzhong Yiqi Decoction containing Hongqi group （Hongqi group）. The mice were injected peritoneally with cyclophosphamide to establish the immunosuppressive models. Huangqi group and Hongqi group were given Buzhong Yiqi Decoction 20ml/kg containing Huangqi and Hongqi respectively for 14 days

while the control group and model group were given normal saline of equal volume. The thymus and spleen weights were measured to calculate the thymus and spleen indices

the phagocytic function of macrophages

serum hemolysin

T lymphocyte proliferation

the activity of NK cells

and the IL-4 were determined of all the above-mentioned indexes （P<0.05 or P<0.01）. Results Comparing with the model group

both BuzhongYiqi Decoction groups were found increase. Except that the T lymphocyte proliferation of the Buzhong Yiqi Decoction containing Hongqi group was stronger than that of the BuzhongYiqi Decoction containing Huangqi group

the other immunologic indices of the two BuzhongYiqi Decoction groups were not statistically different （P>0.05）. Conclusion In improving the cellular immunologic function

Hongqi and Huangqi can replace each other in Buzhong Yiqi Decoction.