HIV-1 infection predisposes to the development of specific types of cancer. Most cancers seen in the AIDS setting are related to oncogenic virus infections, such as Epstein-Barr virus (EBV), Kaposi's sarcoma (KS)-associated herpesvirus (KSHV) and human papillomavirus (HPV). It is generally assumed that HIV-1 infection play a passive role in cancer development by impairing the host immune surveillance and increasing the risk of oncogenic virus infection. Recent insights, however, indicate that HIV-1 infection more actively promotes cancer growth. Experimental evidence has shown that HIV-1-encoded proteins can directly induce tumor angiogenesis and enhance KSHV transmission to target cells. Clinical evidence suggests that the oncogenicity of HPV is altered by the presence of HIV-1 infection irrespective of host immune status. The introduction of highly active antiretroviral therapy (HAART) has dramatically decreased the incidence of KS whereas the impact of HAART is variable in EBV-related lymphoma and HPV-related cervical cancer, suggesting that additional factors are involved in the pathogenesis of these cancers. Understanding the direct and indirect roles of HIV-1 in the pathogenesis of neoplastic conditions could provide the rationale for prevention and development of new treatments for AIDS-associated malignancies.