Lung fibrosis is a common feature of interstitial lung diseases, and apoptosis and fibrinogenesis play critical roles in its formation and progression. Hepatocyte growth factor (HGF) is one of the ideal therapeutic agents for prevention of lung fibrosis because of its antiapoptotic and fibrinolytic effects. The aim of this study is to establish nonviral HGF gene therapy of bleomycin-induced lung fibrosis avoiding the viral vector-related side effects. C57BL/6 mice were injected with 3.0 mg/kg body weight of bleomycin intratracheally. Following bleomycin injection, 50 microl of pUC-HGF (1 mg/ml) was injected into each of the quadriceps muscle. Immediately after plasmid injection, in vivo electroporation was performed with pulse generator. Skeletal muscle-targeting electroporation induced transgene expression on day 1 and persisted for 4 weeks, and human HGF was also detected in the lung. In mice transferred with HGF, pathological score (1.0+/-0.3 vs 3.2+/-0.6), TUNEL-positive cell index (4.5+/-1.1 vs 14.2+/-3.1), and hydroxyproline content (9.0+/-1.3 vs 14.4+/-5.1 micromol/g) were significantly reduced compared with the control. Furthermore, survival rate of HGF mice was significantly improved compared with the control. Our data indicate that HGF gene therapy with a single skeletal muscle-targeting electroporation has a therapeutic potential for bleomycin-induced lung fibrosis and this strategy can be applied as a practical gene therapy protocol for various organs.