<正> Objective: To evaluate the therapeutic effects and mechanisms of Qidan granule in blemycinA5-induced pulmonary interstitial fibrosis （PIF）in rats. Methods: PIF models were established by blemycinA5-induced in rats. They were treated by Qidan granule and Hydrocortisone respectively. The pathological changes and collagen protein disposition were observed

and the expression of TGF-β

TNF-α proteins were measured by immunohistochemical technique . Results: The pulmonary alveolitis and fibrosis were alleviated remarkably in Qidan granule group compared with those in the model control group and hydrocortisone group （P <0. 01）. The expression of TGF-β and TNF-α protein were higher in Qidan granule group than those in normal group

and were significantly less than those in the model control group and in hydrocortisone group （P < 0. 01）. Conclusion: Qidan granule would ameliorate the pulmonary alveolitis and fibrosis. TGF-β and TNF-α might play an important role in the development of alveolitis and fibro