Hodgkin's lymphoma (HL) is a lymphoproliferative disorder of B-lymphocytes. Epstein-Barr virus (EBV) antigens can be detected in tumours in up to 40% of all HL cases. Patients with EBV-associated HL also show increased levels of EBV-infected B-lymphocytes in blood compared with normal individuals and non-EBV-associated HL cases. A peculiar pattern of restricted EBV-antigen expression, dominated by latent membrane protein-1 (LMP-1), LMP-2 and EBV nuclear antigen-1, is the characteristic feature of tumour-specific Hodgkin/Reed-Sternberg cells. This knowledge has generated studies examining adoptive immunotherapy of autologous or allogeneic cytotoxic T-cells for the treatment of refractory EBV-positive HL cases. Whether aborted EBV or another infectious aetiology is involved in non-EBV-associated HL cases remains an open question.