Lymphoproliferative disorders and selected carcinomas which occur as complications of primary or secondary immunodeficiencies are frequently fatal. The incidence rates of these cancers vary from 1% to as high as 25% among specific groups of persons with primary (genetically-determined) immunodeficiencies as well as acquired immunodeficiencies, including immunosuppressed organ transplant recipients and individuals infected with HIV. Lymphoproliferative disorders including Epstein Barr virus (EBV) associated B cell lymphoproliferative disease (BLPD) and Hodgkin's disease represent the predominant category of tumors in both primary and acquired immunodeficiencies. EBV is an important cofactor common to many, but not all, B cell "lymphomas." Immunodeficient individuals who are at risk for developing EBV BLPD may demonstrate both inadequate immune responses to the virus as well as generalized immunoregulatory dysfunction reflected as imbalances in cytokine production favoring the proliferation of transformed B lymphocytes. Historically, the success of treatment of lymphoproliferative disorders in immunodeficiencies with conventional multi agent chemotherapies and/or radiation has been limited by unfavorable tumor response rates and high morbidity and mortality related to intercurrent opportunistic infections. With improvements in supportive care and the use of recombinant biologic response modifiers such as alpha interferon and/or other immunotherapies to treat EBV BLPD, survival of immunodeficient hosts following tumor diagnosis may improve. In addition to lymphoproliferative disorders, patients with congenital immunodeficiencies associated with IgA deficiency (including ataxia telangiectasia and Common Variable Immunodeficiency) are at increased risk for gastrointestinal carcinomas. Early detection and surgical excision of such tumors can result in prolonged survival in such patients.