We have already reported the beneficial effect of hepatic stimulatory substance (HSS) on the proliferation of transplanted hepatocytes into the spleens of rats with CCl4 induced liver cirrhosis (LC) or portocaval shunt. The aim of the study was to investigate the influence of HSS dose and hepatic insufficiency on the proliferation of transplanted hepatocytes into the spleens of rats with CCl4 induced LC.HSS was prepared from regenerating pig livers at 48h after 40% hepatectomy according to the method of LaBrecque et al, and LC was induced in male Wistar rats according to the method of Proctor et al. Hepatocytes (1 10 7 ) isolated from syngeneic rat livers were transplanted into the spleen of rats with CCl4 induced LC. i: To examine the influence of HSS dose, the rats received HSS (3ml iv, 2, 3, or 7d/w) and CCl4 (2d/w) after HTx. ii: To examine the influence of hepatic insufficiency, the rats received CCl4 (2, 3, or 4d/w) and HSS (2/w) after HTx. The animals were sacrificed at 4 weeks after HTx and hepatocyte occupied area ratio (%) on the longitudinal cut surface of the spleens was measured in HE stained sections using an imaging processor.At the 4th week after HTx, HSS treated rats revealed dose-dependent increase in hepatocyte occupied area ratio (1.27, 1.61, and 2.67% for 2, 3, and 7d/w respectively), and that of nontreated rats was only 0.32%. Hepatocyte occupied ratio also increased in proportion to the amount of CCl4 treatment after HTx.In conclusion, the proliferation of intrasplenically transplanted hepatocytes was enhanced in proportion to the dose of HSS and the severity of hepatic insufficiency.