Backgrounds & Objectives: Many acute and chronic lung disorders with variable degrees of pulmonary inflammation and fibrosis are collectively referred to as interstitial lung diseases. Idiopathic pulmonary fibrosis (IPF) is one of several idiopathic interstitial pneumonias with the pathogenesis unclear. Astragali Radix is known to inhibit the Th2 immune response. The effects of Astragali Radix on bleomycin-induced lung fibrosis were evaluated. Materials and Methods: Astragali Radix extract was daily given to the normal rats, control (bleomycin) and treated (bleomycin and Astragali Radix extract, 24.0 mg/10g body weight) rats for 14 days. After 14 days, we observed the change of total leukocyte count and percentage, IFN-gamma and IL-4 in BALF (Bronchoalveolar lavage fluid), and of semiquantitative histological index (SHI). Results: Compared to the control group, Astragali Radix decreased total leukocyte count (p<0.05), lymphocyte (p<0.05), neutrophil (no significance) percentage, SHI (p<0.05), IFN-gamma and IL-4 (p<0.05). Otherwise, macrophage percentage was increased (p<0.01). Conclusion: This study showed that Astragali Radix reduced the incidence of inflammatory cells and cytokines and prevented the fibrosis of tissue in bleomycin-induced lung fibrosis rats.