Objective:To observe the imbalanced T cell-specific transcription factors T-bet and GATA-3 in asthmatic rats and discuss the regulation of the Astragalus membranaceus acts on them. Methods:Fifty male SD rats were randomly divided into Group C(control group),Group A(asthmatic group),Group H1(low-dose Astragalus membranaceus group),Group H2(medium-dose Astragalus membranaceus group) and Group H3(high-dose Astragalus membranaceus group),which were observed the changes of airway histology. CD4+T cells were isolated from twenty male SD rats spleens and incubated with RPMI-1640 at 37℃ for 24 hours,and were divided into 5 groups as noted above. The concentrations of interleukin(IL)-4,IL-5,IFN-γ in serum and CD4+T cells supernatant were measured by enzyme-linked immunosorbent assay(ELISA),while the mRNA expressions of T-bet and GATA-3 were detected by reverse transcription-polymerase chain reaction(RT-PCR),and the protein expressions of T-bet and GATA-3 were detected by western blot respectively. Results:The numbers of eosinophils(EOS) and lymphocytes,the thicknesses of WA/Pi and ASM/Pi of Group A,were significantly elevated compared with those of Group C(P < 0.01). The EOS and lymphocytes,the thicknesses of WA/Pi and ASM/Pi of Group H1-3 were lower than those of Group A. The IL-4 and IL-5 concentrations of Group A were significantly elevated compared with those of Group C,and those of Group H1-H3 were lower than Group A(P < 0.01). Compared with Group C(P < 0.01),the significantly lower concentration of IFN-γ in Group A was detected,and the Group H1-3 had the higher concentrantions of IFN-γ than Group A(P < 0.01). In CD4+T cells supernatant,the concentrations of IL-4 and IL-5 were distinctly decreased and the concentrantions of IFN-γ were increased in the Group H1-3. There were obvious differences in the concentrations of IL-4,IL-5 and IFN-γ between the Group H1-3 and Group A(P < 0.01). In Group H1-3,the expressions of T-bet mRNA and protein in lungs and CD4+T cells were obviously increased compared with those of Group A (P < 0.01);and the Group H1-3 has the lower levels of GATA-3 mRNA and protein expressions than Group A(P < 0.01). Conclusion:In asthma the imbalanced T cell-specific transcription factors T-bet and GATA-3 play a key role in Th2 polarization with over-production of Th2-like cytokines. Astragalus membranaceus inhibits the asthmatic airway inflammation with regulating the balance of transcription factors T-bet and GATA-3.