The Epstein-Barr virus (EBV) is a human herpes virus with the ability to transform B-lymphocytes in vitro. EBV has been linked to the pathogenesis of a variety of human tumours, including Burkitt's lymphoma, immunosuppression-related lymphomas, Hodgkin's disease, nasal angiocentric T/NK-cell lymphoma and nasopharyngeal carcinoma. Based on the association of the virus with these tumours, EBV has been classified as a group 1 carcinogen by the WHO International Agency for Research on Cancer. In this article, the evidence suggesting that EBV is carcinogenic to humans is briefly reviewed.