Acquired immunodeficiency syndrome (AIDS)-associated malignancies are a concern to all physicians. Because patients usually are seen initially by nonspecialists, primary care physicians, especially, may find useful information about AIDS-related malignancy. Cancers remain a part of the clinical definition of AIDS. Kaposi's sarcoma (KS) and non-Hodgkin's lymphomas are the malignancies most frequently seen in AIDS. Acquired immunodeficiency syndrome KS occurs in young men between 20 and 40 years of age, and involves the skin in more than 90% of patients. Visceral dissemination is common. The prognosis is related to immune functional status and the extent of disease involvement. Acquired immunodeficiency syndrome-related non-Hodgkin's lymphoma is generally a B-cell malignancy. Advanced disease at presentation and proclivity for central nervous system involvement are characteristic. Knowledge of the common manifestations of these cancers, methods of diagnosis, and potential treatment options is important for physicians.