Epstein-Barr virus has been classically associated with certain B-lymphocytic benign and malignant proliferations. However, using molecular biological techniques it becomes clear that EBV is also associated with several T-NHL in non-immunocompromised patients. The distribution of EBV-associated T-NHL seems to be site-restricted, i.e. in about 100% of the nasal T-NHL and in 20% of the lung and gastrointestinal lymphomas and rarely in primary cutaneous T-cell lymphomas. Moreover, the expression of the LMP1 protein seems to be associated with a poor prognosis. In this section the role of EBV in the pathogenesis of T-NHL will be discussed.