Objective:To investigate the effect of silibinin on the expression of connective tissue growth factor(CTGF) and the secretion of type Ⅲ collagen in HK-2 cells induced by TGF-β1. Methods:In vitro,HK-2 cells were divided into three groups:①control group;②5 ng/ml TGF-β1 group; ③5 ng/ml TGF-β1+silibinin with different concentrations group, 5 μg/ml,10 μg/ml and 20 μg/ml,respectively. 48 h later,the expression of CTGF mRNA in cells were detected by reverse transcription-po1ymerase chain reaction(RT-PCR);the concentrations of CTGF and collagen Ⅲ secreted into the culture supernatant was determined by ELISA. Results:Compared with control group,the expression of CTGF mRNA and the concentration of the secreted collagen Ⅲ and CTGF were all increased markedly in the group of TGF-β1 treatment(P < 0.01). Compared with TGF-β1 group,the different concentrations of(5 μg/ml,10 μg/ml and 20 μg/ml) silibinin could also effectively suppress the expressions of CTGF mRNA and the concentration of the secreted collagen Ⅲ and CTGF(P < 0.01) in a dose-dependent manner. And the 20 μg/ml silibinin group had the most prominent effect. Conclusion:Silibinin could suppress the expressions of collagen Ⅲ and CTGF induced by TGF-β1. It is suggested that silibinin might exert an inhibitive effect on renal fibrosis,which may be related with its role in reducing the expression of CTGF and preventing accumulation of ECM.