Background/aims: Hepatic fibrosis results from the excessive secretion of matrix proteins by hepatic stellate cells (HSCs), which proliferate during fibrotic liver injury. Transforming growth factor (TGF)-beta 1 is the dominant stimulus for extracellular matrix (ECM) production by stellate cells. Our study was designed to investigate the antifibrotic effects of using short interference RNA (siRNA) to target TGF-beta 1 in hepatic fibrosis and its mechanism in rats exposed to a high-fat diet and carbon tetrachloride (CCL4). Methods: A total of 40 healthy, male SD (Sprague-Dawley) rats were randomly divided into five even groups containing of eight rats each: normal group, model group, TGF-beta 1 siRNA 0.125 mg/kg treatment group, TGF-beta 1 siRNA 0.25 mg/kg treatment group and TGF-beta 1 siRNA negative control group (0.25 Mg/kg). CCL4 and a high-fat diet were used for 8 weeks to induce hepatic fibrosis. All the rats were then sacrificed to collect liver tissue samples. A portion of the liver samples were soaked in formalin for Hematoxylin-Eosin staining, classifying the degree of liver fibrosis, and detecting the expression of type I and III collagen and TGF-beta 1; the remaining liver samples were stored in liquid nitrogen to be used for detecting TGF-beta 1 by Western blotting and for measuring the mRNA expression of type I and III collagen and TGF-beta 1 by quantitative real-time polymerase chain reaction. Results: Comparing the TGF-beta 1 siRNA 0.25 mg/kg treatment group to the model group, the TGF-beta 1 siRNA negative control group and the TGF-beta 1 siRNA 0.125 mg/kg treatment group showed significantly reduced levels of pathological changes, protein expression and the mRNA expression of TGF-beta 1, type I collagen and type III collagen (P < 0.01). Conclusions: Using siRNA to target TGF-beta 1 can inhibit the expression of TGF-beta 1 and attenuate rat hepatic fibrosis induced by a high-fat diet and CCL4. A possible mechanism is through the down-regulation of TGF-beta 1 expression, which could inhibit HSC activation, as well as the proliferation and collagen production of collagen reducing, so that collagen deposition in the liver is reduced. (C) 2011 Elsevier Inc. All rights reserved.