Hepatocyte growth factor (HGF) has various effects especially on epithelial cells. However, the precise role of HGF on lipogenesis is still not fully understood. A high-fat diet was administered to HGF transgenic mice and wild type control mice in vivo. Furthermore, recombinant human HGF (rhHGF) was administered to a HepG2 cell line in vitro. We performed an analysis regarding the factors relating to lipid metabolism. Overexpression of HGF dramatically ameliorates a high-fat diet-induced fatty liver. HGF transgenic mice showed an apparently reduced lipid accumulation in the liver. The activation of microsomal triglyceride transfer protein (MTP) and apolipoprotein B (ApoB) accompanying higher triglyceride levels in the serum were found in HGF transgenic mice on a normal diet. Interestingly, this up-regulation of the MTP activation became more apparent in the high-fat diet. In addition, the administration of rhHGF stimulated MTP and ApoB expression while reducing the intracellular lipid content in the HepG2 cell line. However, this induction of MTP and ApoB by HGF was clearly inhibited by PD98059 (MAPK inhibitor). In conclusion, the data presented in this study indicated that HGF ameliorates a high-fat diet-induced fatty liver via the activation of MTP and ApoB.