Development of a vaccine against Epstein-Barr virus (EBV) is constrained by the latency phenotypes adopted by different EBV-associated diseases. Over the last few years an immense body of information on the pattern of viral gene expression in EBV-associated diseases and the role of cytotoxic T cells in the control of these diseases has accumulated. It would seem reasonable to suggest that emerging technologies are at a level where vaccine trials aimed at controlling infectious mononucleosis, post-transplant lymphoproliferative disease, nasopharyngeal carcinoma and Hodgkin's disease are justified. On the other hand, a more cautious approach may be required for the development of vaccines or immunotherapeutic strategies against Burkitt's lymphoma.