OBJECTIVE To investigate the effect of retrorsine on the proliferation of SD rat immortalized hepatocytes after intrasplenic transplantation. METHODS Immortalized hepatocytes from SD rats was prepared by transfecting the primary hepatocytes with a retroviral vector SSR69 expressing the genes encoding Simian virus 40 T large antigen. Twenty-four adult SD rats were randomly assigned to 3 equal groups designated respectively as A, B, and C groups. Intraperitoneal retrorsine injections at the dose of 26 mg/kg.b.w. were performed twice in groups A and B at the interval of two weeks before hepatocyte transplantation. After 20% hepatic lobe resection were completed in all the groups, groups A and C received intraplenic transplant with immortalized hepatocytes, while group B received normal hepatocyte transplant. Post-mortem examinations were performed on the spleen samples with HE staining. Albumin expression in the transplanted hepatocytes was examined by immunohistochemical staining, and the ultrastructure of the transplanted cells was observed under transmission electron microscope. RESULTS Histological examination demonstrated that the rat spleens in all the 3 groups contained cluster of transplanted hepatocytes from 1 week to 3 weeks after the transplantation, and the proliferation of the transplanted cells were comparable between groups A and B, but both of which showed significant difference from group C. Albumin excretion by the immortalized hepatocyte was identified in all the groups, and the transplanted immortalized cells preserved normal cell ultrastructure. CONCLUSIONS Immortalized hepatocytes of SD rat have the normal cell ultrastructure and albumin-excretion function, and retrorsine can promote the proliferation of the transplanted hepatocytes.