OBJECTIVE The aim of this study was to investigate the preventive actions of bezafibrate against non-alcoholic steatohepatitis (NASH), the activation of hepatic stellate cells (HSC), and fibrogenesis by using a model of NASH and an in vitro model. METHODS Male KK-A(y)/TaJcl (KK-A(y)) mice were fed a methionine and choline-deficient (MCD) diet or a MCD diet containing bezafibrate or pioglitazone for 7 weeks, after which biochemical parameters, pathological changes, and hepatic mRNA levels were assessed. An in vitro HSC model was designed by using a previously described RI-T cell line stimulated by transforming growth factor-beta1 (TGF-beta1). RESULTS MCD diet-fed KK-A(y) mice developed hepatic steatosis, oxidative stress, inflammation, and hepatic fibrosis. Bezafibrate markedly decreased the hepatic content of triglyceride accumulation of fatty droplets within hepatocytes, and increased the expression of hepatic fatty acid beta-oxidative genes in MCD diet-fed KK-A(y) mice. Bezafibrate markedly inhibited the increases in the plasma alanine aminotransferase level and hepatic content of thiobarbituric acid-reactive substances in this model. Moreover, it dramatically reduced hepatic inflammatory changes and fibrosis concomitantly with marked reductions in the mRNA levels for inflammatory cytokine, chemokine, and profibrogenic genes. Importantly, both bezafibrate and pioglitazone markedly reduced the mRNA levels of profibrogenic and fibrogenic genes in TGF-beta1-stimulated cells. CONCLUSIONS Bezafibrate improved hepatic steatosis and potently prevented inflammation, oxidative stress, HSC activation, and fibrogenesis in the liver. Moreover, this study was the first to demonstrate that bezafibrate directly inhibits hepatic fibrogenic response induced by TGF-beta1 in vitro. Hence bezafibrate may be a new therapeutic strategy against NASH and hepatic fibrosis.