Objective : Idiopathic Lung Fibrosis(IPF) is chronic fibrotic interstitial pneumonia. The pathogenesis is unclear. Lonicerae Flos is known to prevent the inflammation and reinforce the immune system. The effects of Lonicerae Flos on bleomycin-induced lung fibrosis is evaluated. Material and Methods: Lonicerae Flos extract was given to the Normal rats, control(bleomycin) rats everyday and treated(bleomycin and lonicerae flos) rats 21.0 mg per body weight 109 for 14 days. 14 days after, we observed the change of leukocyte count and percentage of IFN-gamma and IL-4 in BALF. and that of Semiquantative histological index(SHI). Results : Compared to control rats, Lonicerae Flos decreased leukocyte count(P<0.01) lymphocyte, neutrophil percentage(P<0.05), SHI(P<0.01), IFN-gamma and IL-4(P<0.05) in Treated rats. Otherwise, macrophage percentage was increased(P<0.01) in Treated rats. Conclusion : This study showed that Lonicerae Flos reduced the change of inflammatory cells and cytokines in bleomycin-induced lung fibrosis and reduced the fibrosis of tissue. And, we needed many other distinct researches on lung fibrosis.