Epstein-Barr virus (EBV), one of 8 known human herpesviruses, infects the vast majority of mankind and infections are generally subclinical. However, EBV infection has been associated with a spectrum of diseases, lymphoproliferative diseases (EBV-LPD) in particular, including malignant lymphoma. EBV-LPD are frequently observed in patients with primary or secondary immunodeficiencies. The incidence of EBV-LPD is on the rise, partly because of increasing numbers and success of hematopoietic stem cell and solid organ transplants and partly because many patients with immunodeficiencies, both primary and secondary, including AIDS, live longer, with improvements in supportive care. Herein, a spectrum of EBV-associated diseases in patients with immunodeficiency are summarized and discussed mainly focusing on their pathogenetic mechanism(s).