In this study, fasudil administration significantly (1) improved histopathological features and decreased hydroxyproline content in the lungs of bleomycin-treated mice; (2) attenuated infiltration of inflammatory cell numbers in the BALF; and (3) reduced the production of TGF-β1, CTGF, α-SMA, and PAI-1 mRNA and protein expression in bleomycin-induced pulmonary fibrosis. The gene discussed is SERPINE1; the disease is pulmonary fibrosis.