In order to investigate the human cytomegalovirus (HCMV) infection, the mouse cytomegalovirus (MCMV) infected mice were experimentally studied. 6 to 8 week old female BALB/C mice with immunosuppression were selected to undergo the MCMV inoculations: intracranial inoculation and peritoneal inoculation. MCMV of the infected mice in various organs and tissues were detected by using  gal staining and in situ nucleic acid hybridization assay. The pathological cha nges were observed in HE staining paraffin embedded sections. It was found that all the MCMV infected mice showed the retardation of growth and development, an d feather looseness. Both intracranial inoculation of 10 4 PFU viruses or perit oneal inoculation of 10 6 PFU viruses resulted in the pathological changes, to some extent, of various organs and tissues in the mice. The pathological changes in liver were consistent with the amount of  gal staining positive cells, in dicating the liver lesions were mainly caused by viral proliferation. It was als o found that the viruses in the immunosuppressed mice subjected to intracranial inoculation could spread to whole body organs, while the viruses in the immunosu ppres sed mice subjected to intrapeitoneal inoculation couldn’t spread to the brain, s uggesting blood brain barrier could prevent the virus from spreading to the bra in. In order to investigate the human cytomegalovirus (HCMV) infection, the mouse cytomegalovirus (MCMV) infected mice were experimentally studied. 6 to 8 week old female BALB / C mice with immunosuppression were selected to undergo the MCMV inoculations: intracranial inoculation and peritoneal inoculation. MCMV of the infected mice in various organs and tissues were detected by using  gal staining and in situ nucleic acid hybridization assay. The pathological cha nges were observed in HE staining paraffin embedded sections. It was found that all the MCMV infected mice showed the retardation of growth and development, an feather looseness. Both intracranial inoculation of 10 4 PFU viruses or peritoneal inoculation of 10 6 PFU viruses resulted in the pathological changes, to some extent, of various organs and tissues in the mice. The pathological changes in liver were consistent with the amount of  gal staining positive cells, in dicating the liver lesions were mainl y was by viral proliferation. It was als o found that the viruses in the immunosuppressed mice subjected to intracranial inoculation could spread to whole body organs, while the viruses in the immunosuppres sed mice subjected to intrapeitoneal inoculation could not spread to the brain, s uggesting blood brain barrier could prevent the virus from spreading to the bra in.