Although the exact incidence of cancers in human immunodeficiency virus (HIV)-infected children is not clear, an excess of non-Hodgkin's lymphomas and soft tissue tumors as well as a multitude of otherwise rare tumors in childhood, such as cervical, thyroid, or pulmonary carcinoma, has been reported. In contrast to the findings in HIV-infected adults, Kaposi's sarcoma is rare in children in industrialized countries but not in children living in the sub-Saharan area. Treatment of the neoplastic disease is often complicated by multiple HIV-associated organ dysfunctions as well as drug interactions and infectious complications secondary to severe immunosuppression. Nonetheless, preliminary results with dose-intensive, but brief, chemotherapeutic regimens have been encouraging, and HIV-infected children who develop cancer are likely to benefit from aggressive treatment combined with adequate supportive care. Furthermore, insights gained from the study and treatment of this very challenging group of patients may benefit other immunocompromised hosts as well as increase our understanding of oncogenesis in general.