To evaluate the therapeutic effect and mechanism of folium Ginkgo biloba (FGB) in treating pulmonary interstitial fibrosis (PIF) induced by bleomycin in rats. [WT4”HZ]Methods: PIF models of bleomycin A 5 induced pulmonary fibrosis were established in rats, they were treated by Bailuda, a preparation of FGB, and the pathological changes, collagen protein level, nuclear factor kB(NF kB) activity, transforming growth factor β (TGF β) mRNA expression and protein level of the lung tissue were measured. [WT4”HZ]Results: In the Bailuda treated group after treatment, amelioration of the pulmonary alveolitis and fibrosis were shown in pathological section (P<0 05) and collagen protein content was lesser (P<0 01) as compared with those in the model control group. After 1 week of Bailuda treatment, the NF kB activity of pulmonary alveola macrophage lowered by 47.3%, and levels of TGF β mRNA expression and protein were all decreased (P<0 05). [WT4”HZ]Conclusions: Bailuda has definite effect in treating PIF. The mechanism may be through inhibiting the activity of NF kB, decreasing TGF β mRNA expression and protein, so as to ameliorate the inflammation and fibrosis. To evaluate the therapeutic effect and mechanism of folium Ginkgo biloba (FGB) in treating pulmonary interstitial fibrosis (PIF) induced by bleomycin in rats. [WT4 “HZ] Methods: PIF models of bleomycin A 5 induced pulmonary fibrosis were established in rats, they were treated by Bailuda, a preparation of FGB, and the pathological changes, collagen protein level, nuclear factor kB (NF kB) activity, transforming growth factor β (TGFβ) mRNA expression and protein level of the lung tissue were measured. ”HZ] Results: In the Bailuda treated group after treatment, amelioration of the pulmonary alveolitis and fibrosis were shown in pathological section (P <0 05) and collagen protein content was lesser (P <0 01) as compared with those in the model control group. After 1 week of Bailuda treatment, the NF kB activity of pulmonary alveola macrophage lowered by 47.3%, and levels of TGF β mRNA expression and protein were all decreased (P <0 05). [WT4 "HZ] Conclusions: Bailuda has def inite effect in treating PIF. The mechanism may be through inhibiting the activity of NF kB, decreasing TGF β mRNA expression and protein, so as to ameliorate the inflammation and fibrosis.