In a previous study, we generated a mutant of dHGF (deleted variant of hepatocyte growth factor), termed #2, with higher specific activity than dHGF in assays of mitogenic activity on rat hepatocytes and America opossum kidney epithelial cells (OK). In the present study, we examine in vivo hepatotropic and renotropic activities of #2 and its distribution to target tissues, liver and kidney. Administration of #2 to normal rats significantly increased serum levels of total protein, albumin, free-cholesterol, and HDL-cholesterol and liver weight in a dose-dependent manner. Analysis of these parameters suggests that #2 is more potent than dHGF as a hepatotropic factor in vivo. In addition, #2 reduced mortality of mercuric chloride-administered mice and the effect was stronger than that of dHGF. When injected to mice, a larger amount of #2 than dHGF was rapidly distributed to the liver. Sixty minutes after injection, the concentrations of #2 in plasma, liver, and kidney were higher than those of dHGF. These distribution properties and the higher mitogenic activity in vitro may explain why #2 exerts more potent in vivo biological activity than dHGF.