Objective To study the effect and mechanism of Kangxianling on renal interstitial fibrosis （RIF）.Methods Kangxianling serum

fosinopril serum and normal serum was prepared respectively with intragastric administration of 3.2g/ml Kangxianling

3.3mg/ml fosinopril and distilled water to rats. The serum was diluted with a DMEM medium and divided into the normal group

fosinopril group

Kangxianling group

transforming growth factor-β1 （TGF-β1） group

TGF-β1+fosinopril group and TGF-β1+Kangxianling group. The bone marrow-derived fetal bovine serum （FBS） was studied. The expressions of α-smooth muscle actin （α-SMA） and Collagen I were examined by enzyme-linked immunosorbent assay （ELISA） and real time polymerase chain reaction （RT-PCR）.Results Comparing with the normal group

the expressions of α-SMA

Collagen I

α-SMA mRNA and Collagen I mRNA were significantly improved in the TGF-β1 group （P<0.05 or P<0.01）. Comparing with the TGF-β1 group

the expressions of α-SMA

Collagen I

α-SMA mRNA and Collagen I mRNA were significantly decreased in the TGF-β1+fosinopril group and TGF-β1+Kangxianling group （P<0.05 or P<0.01）.Conclusion fKangxianling can antagonize RIF by inhibiting phenotypic transformation of bone marrow-derived FBS.