Objective: To explore mechanism of the effect of Fuzheng Huayu Decoction on Ito cell proliferation and collagen synthesis.Methods: Biological effects of the drug serum taken from rats fed with Fuzheng Huayu decoction (FZHYD) on cell proliferation and collagen synthesis of Ito cell line were observed. Serum collected from rats at various times (1

2 or 3 hours) after animals were fed with FZHYD once (It) or twice (2t

2nd time repeated with the same dose)

was incubated with Ito cell.Results: The lt-2h serum in 0. 46 g/kg FZHYD group

it seems to prevent cell proliferation

but had no significant difference. While all 2t drug serum could inhibit cell proliferation. The 2t-lh drug serum had no obvious effects on Ito cell morphology

but could improve cell viability

its effect on cell proliferation was dose and serum concentration dependent. Also the 2t-lh drug serum in all doses could inhibit Ito cells both intracellular and extracellular collagen production

the drug serum of 0.46 g/kg group had inhibitory effect in serum concentration dependent manner and similar effect as colchicine.Conclusion: Inhibition of Ito cells proliferation and collagen synthesis is perhaps one of main mechanism of FZHYD in antifibrotic action.