AIM: To evaluate the therapeutic effect of Chunggan extract (CGX), a modified traditional Chinese hepatotherapeutic herbal, on the dimethylnitrosamine (DMN)-induced chronic liver injury model in rats.METHODS: Liver injuries were induced in Wistar rats by injection of DMN (ip, 10 mg/mL per kg) for 3 consecutive days per week for 4 wk. The rats were administered with CGX (po, 100 or 200 mg/kg per day) or distilled water as a control daily for 4 wk starting from the 15th d of the DMN treatment. Biochemical parameters (serum albumin, bilirubin, ALP, AST and ALT), lipid peroxides,hydroxyproline, as well as histological changes in liver tissues were analyzed. In addition, gene expression of TNF-α, TGF-β, TIMP-1, TIMP-2, PDGF-β, and MMP-2, all of which are known to be associated with liver fibrosis,were analyzed using real-time PCR.RESULTS: CGX administration restored the spleen weight to normal after having been increased by DMN treatment.Biochemical analysis of the serum demonstrated that CGX significantly decreased the serum level of ALP (P＜ 0.05), ALT (P ＜ 0.01), and AST (P ＜ 0.01) that had been elevated by DMN treatment. CGX administration moderately lowered lipid peroxide production and markedly lowered hydroxyproline generation caused by DMN treatment in accordance with histopathological examination. DMN treatment induced a highly upregulated expression of TNF-α, TGF-β, TIMP-1, TIMP-2,PDGF-β, and MMP-2. Of these, the gene expression encoding PDGF-β and MMP-2 was still further enhanced 2 wk after secession of the 4-wk DMN treatment, and was remarkably ameliorated by CGX administration.CONCLUSION: CGX exhibits hepatotherapeutic properties against chronic hepatocellular destruction and consequential liver fibrosis.