Hepatocellular transplantation into the spleen was investigated as a new attempt in utilizing isolated hepatocytes to compensate for impaired liver function. Present study was undertaken to evaluate morphological and histochemical alterations up to 6 weeks following transplantation in hepatocytes transplanted into the splenic parenchyma. Light microscopic studies revealed viable hepatocellular islets in the splenic parenchyma up to 6 weeks, although minimal cytoplasmic changes were observed. Electron microscopic studies demonstrated moderate changes in organelles, which developed gradually as the time after transplantation proceeded. Distortion and fragmentation of the membranes around the cytoplasm and organelles were not recognized. Moreover, newly formed bile canaliculi and tight junctions which indicate reconstruction of hepatic plates were observed between adjacent cell membranes, and enzyme activities were detected by cytochemical determination of glucose-6-phosphatase in the hepatocytes even 6 weeks after transplantation. The transplanted hepatocytes preserved their characteristic enzyme and fine structures as hepatocytes up to 6 weeks. Our present study based on the persistence of cellular viability suggests that inoculated hepatocytes do maintain their hepatocellular functions after transplantation.