HHV-6 presence in plasma or serum was documented in 33-48% of hemopoietic stem cell transplant (HSCT) recipients using molecular techniques [22] . The peak viral load occurs early after transplantation and usually within the first four weeks after transplantation [4, 21] . Allogeneic SCT, advanced hematological disease, young age, gender mismatch between the donor and recipient, and treatment with corticosteroids are commonly reported risk factors associated with HHV-6 infection after transplantation [4, 21] .