Objective To compare the immunoregulatory effects of Radix Millettia Speciosa (RM Speciosa) and Radix Millettia Championi (RM Championi)on immunosuppressed mice.Methods Kunming mice were randomly divided into normal control group,CTX model group,LMS positive group,RM Speciosa groups and RM Championi groups (20,10 and 5 g/kg).The mice were treated respectively with drug or NS once a day for consecutive 20 days.Mice in the other groups were injected intraperitoneally with CTX at days 8,10 and 12 to establish immunosuppressed mice model except the normal group.The changes of body weight,immune organ weight,white blood cell (WBC)number,carbon particle clearance capability of macrophages and delayed type hypersensitivity (DTH)of mice in all groups were determined and compared.Results Compared with that in CTX group,the WBC number was significantly increased (P<0.01 or P<0.05)and the degree of DTH (P<0.01) was enhanced at different doses in RM Speciosa groups and RM Championi groups.The activity of macrophages and the index of thymus and spleen were also improved in the treatment groups (P<0 .0 5 or P<0 .0 1 ).The index of thymus and the degree of DTH in RM Speciosa groups (20 and 10 g/kg)were slightly higher than those in the corresponding RM Championi groups (P<0.01 or P<0.05).For other indicators,RM Speciosa groups did not significantly differ from RM Championi groups (P>0.05).Conclusion Both RM Speciosa and RM Championi can improve the immune function of CTX-induced immunosuppressed mice,and RM Speciosa is slightly superior to RM Championi in improving specific cellular immunity.