ABSTRACT Epstein-Barr virus (EBV) infection is extremely common worldwide. Although primary EBV infection is best known in adolescent and young adults, infection occurs more commonly in children, usually without recognizable symptoms, and may also affect older persons. An EBV infection can vary from mild symptoms to a life threatening disease in immunocompromised patients. EBV infection not only causes heterophile-positive infectious mononucleosis, but can also present in a number of other ways. Between 1% and 15% of transplant recipients develop EBV-assosiated lymphoproliferative disease. AIDS patients may develop lymphomas associated with EBV infection. But individuals without AIDS can develop Burkitt`s lymphomas and Hodgkin`s lymphomas which contain EBV DNA. Since the number of immunocompromised patients is increasing and since almost everybody is infected with the EBV worldwide it is important to develop some kind of terapy. Today trials are testing different kinds of therapies with the aim of reducing the infection and to create immunity.