Abstract: Objective To investigate the effects of chlorogenic acid (CGA) on hepatic stellate cell proliferation and the expression and secretion of Collagen Ⅰ, Collagen Ⅲ, tissue inhibitors of metalloproteinase-1 (TIMP-1) and matrix metalloproteinase-2 (MMP-2). Methods An immortalized rat hepatic stellate cell (HSC) line was cultured In vitro. The cells were divided into 5 groups: control group; platelet-derived growth factor (PDGF) (10 ng/mL), PDGF+CGA (12.5 μg/mL), PDGF+CGA (25 μg/mL), PDGF+CGA (50 μg/mL) and CGA (50 μg/mL) group. After 24 hours treatment, the proliferation of HSC was detected by MTT method. The mRNA expression of Collagen Ⅰ, Collagen Ⅲ, TIMP-1 and MMP-2 were detected by RT-PCR. The protein levels of Collagen Ⅰ, Collagen Ⅲ, TIMP-1 and MMP-2 in the culture supernatant of HSC were measured by ELISA. Results PDGF increased the hepatic stellate cell proliferation, the mRNA expression and the protein levels of Collagen Ⅰ, Collagen Ⅲ and TIMP-1 (P<0.05), which were significantly decreased by CGA (P<0.05). However, CGA had no significant influence on the expression of MMP-2. Conclusion The antifibrotic effect of CGA may be related with the inhibition of hepatic stellate cell proliferation and generation of extracelluar matrix and promotion of extracelluar matrix degradation.