Although high-grade non-Hodgkin's lymphoma (NHL) and an unusually aggressive form of Kaposi's sarcoma (KS) remain the most common malignancies seen in AIDS patients, other tumors such as cervical cancer, Hodgkin's disease and others, have been increasingly observed, probably because these patients now live longer. We report the imaging findings of 80 AIDS patients with pathologically confirmed neoplasms from a series of 340 AIDS patients examined 1986-1994. Twenty-four of 80 patients had NHL, 4 Hodgkin's disease, 31 KS, 4 cervical cancer, 2 leukemia, 2 testicular, 1 larynx, 2 lung, 2 breast, 1 esophagus, 1 stomach, 1 liver, 2 kidney and 3 adrenal carcinomas. Twenty of 24 NHLs exhibited extranodal involvement--to the liver (13/24), brain (9/24), lung (7/24) and gastrointestinal tract (6/24). Visceral KS involved the gastrointestinal tract (6/32), lung (4/32) and liver (2/32). The most accredited pathogenetic theories concerning the role of HIV infection in oncogenesis advocate the effect of multiple growth factors produced by HIV-infected lymphocytes (KS) or the disregulation of B-cells caused by T-cell destruction (NHL). The atypical morphostructural features of AIDS-related tumors are discussed--e.g., atypical presentation, occurrence in younger individuals, aggressive clinical course and poor response to conventional therapy--together with the differential diagnostic problems, especially vs. opportunistic infections.