Epstein-Barr virus-related post-transplant lymphoproliferative disorder (EBV-PTLD) is an uncommon, but frequently fatal, complication after allogeneic hematopoietic stem cell transplant. Prospective post-transplant virological and immunological monitoring allowed to successfully manage a patient who developed both polymorphic and monomorphic, "diffuse large B-cell lymphoma like", as an EBV-PTLD, 65days after allogeneic bone marrow transplant. Early detection of significant increase in EBV DNA level in patient's peripheral blood (peak of viral load equal to 119,039copies/mL whole blood, +56day after transplant) led to administration of pre-emptive anti-CD20 monoclonal antibody (rituximab) and close clinical monitoring. After one week, physical exam revealed laterocervical adenopathy. Histopathologic features, immunohistochemical characterization and in situ hybridization study allowed to establish a diagnosis of EBV-related PTLD. Immunological monitoring showed no EBV-specific T-cell responses during EBV replication, thus potentially explaining the occurrence of high EBV load with subsequent PTLD development. A total of four doses of anti-CD20 monoclonal antibody were administered and at the end of the treatment, EBV infection was cleared and imaging technique showed complete disease remission. In conclusion, the early use of anti-CD20 monoclonal antibody proved to be a safe and effective treatment strategy for EBV-PTLD. Moreover, combined virological-immunological monitoring of EBV infection may more accurately assess patients at higher risk for EBV-PTLD.