In order to understand the mechanism of congenital human cytomegalovirus (CMV) infection we studied the effect of CMV on epithelial cell culture of the endometrium. Endometrial cells proved to be sensitive to CMV as indicated by morphologic alterations, success to support growth of infectious virus and positive immunoperoxidase staining. The infected cells were enlarged, multinuclear and revealed intranuclear inclusions. Electron microscopy detected the presence of the viral particles in the CMV-infected endometrial cells. The possibility that CMV infection of the endometrial cells may play a role in transmitting the virus to the embryo will be discussed.