Kaposi's sarcoma, first described in 1972, is a rare, chronic neoplasm that occurs most often in elderly men of Eastern European origin. In the mid-twentieth century, more aggressive forms of Kaposi's sarcoma were found to be an endemic disease especially common among young black men in central Africa. Kaposi's sarcoma also occurs in iatrogenically immunosuppressed patients, such as kidney transplant recipients. In 1981, the sudden occurrence of an unusual, disseminated form of Kaposi's sarcoma in homosexual men in New York and California heralded the epidemic now known as the acquired immunodeficiency syndrome (AIDS). Ninety-five percent of all AIDS-associated Kaposi's sarcoma (AIDS-KS) has been in homosexual men; however, the incidence of AIDS-KS has diminished from greater than 40% of men with AIDS since 1981 to less than 20% in 1989. The remaining 5% of AIDS-KS has been seen in all other populations at risk for AIDS. The reasons for the remarkable persistent increased prevalence of AIDS-KS among homosexual men remains obscure. Clinically, AIDS-KS is a highly varied neoplastic disease characterized by multifocal mucocutaneous lesions often with lymphatic and visceral involvement. The etiology of Kaposi's sarcoma remains unknown although various hypotheses have been suggested, including endothelial-tumor growth factors, oncogenic expression, genetic predisposition, and environmental cofactors. An as-yet unidentified viruslike agent has been proposed as a possible direct cause of this neoplasm. Different treatment modalities for Kaposi's sarcoma have been employed with varying success, these include localized radiation therapy, cryotherapy, electrocauterization, surgical excision, and a variety of systemic chemotherapeutic regimens, as well as alpha-interferon. Although all available treatments help control the lesions, none lengthens survival.