The antifibrotic effects of hot water extract (WEC), intracellular biopolymer (IPC) and extracellular biopolymers (EPC) from mycelial liquid culture of Cordyceps militaris on liver fibrosis were studied. Liver fibrosis was induced by a bile duct ligation and scission (BDL/S) operation, duration of 4 weeks in rats. In BDL/S rats, the levels of aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), total bilirubin in serum and hydroxyproline content in liver were dramatically increased. The WEC or IPC treatment (30mg/kg/day for 4 weeks, p.o.) in BDL/S rats reduced the serum AST, ALT and ALP levels significantly (p<0.01). The EPC treatment (30 mg/kg /day for 4 weeks, p.o.) reduced the serum ALT, AST and ALP levels significantly (p<0.01). Malondialdehyde contents in liver treated with WEC, IPC or EPC were significantly reduced (p <0.05). But Liver hydroxyproline content was decreased only in EPC treated BDL/S rats to 55% that of BDL/S control rats (p < 0.01). The morphological characteristics and expression of alpha smooth muscle like actin in fibrotic liver, which appeared in BDL/S control group were improved in EPC treated fibrotic liver. These results indicate that IPC (30 mg/kg /day for 4 weeks, p.o.) has an antifibrotic effect on fibrotic rats induced by BDL/S.