Hematopoietic stem cell transplantation (HSCT) bears a risk of reactivating latent cytomegalovirus (CMV) in either the transplanted hematopoietic donor cells or in parenchymal and stromal tissue cells of the immunocompromised recipient, or in both. While reactivated human CMV in recipients of organ transplantations is frequently the virus variant of the donor, this is not usually the case in HSCT recipients. Here we have used experimental sex-mismatched HSCT in the BALB/c mouse model to test if latent murine CMV from CMV-immune donors is transmitted with bone marrow cells to naive immunocompromised recipients.