Epstein-Barr virus (EBV), a B-lymphotropic herpesvirus widespread in human populations, is carried by most individuals as an asymptomatic lifelong infection. Much progress has been made in our understanding of virus infection/persistence, and in the role of the cytotoxic T lymphocyte response in control of that infection. This same virus is linked to several malignancies, including endemic Burkitt's lymphoma, post-transplant lymphoproliferative disease and to many cases of Hodgkin's disease (HD). Recent evidence showing that HD, like the other EBV-associated lymphomas, is of B-cell origin suggests that the pathogenesis of these malignancies may share more common ground than previously thought. The biology and cytotoxic T-cell control of primary and persistent EBV infection, and the links between EBV and all three lymphomas are reviewed. The expression of viral antigens in EBV-positive HD raises the possibility of developing tumour immunotherapy, using relevant components of the EBV-specific T-cell response; progress to date, and future prospects for immune control of EBV-positive HD are discussed.