Several viruses have been detected, at various frequencies, in Kaposi's sarcoma (KS) tissues. The detection of human herpesvirus 8 (HHV-8) in all the epidemiological and histological forms of KS makes it the most attractive candidate causative agent to date. In this report, we discuss the possible explanations for the detection of genomic sequences of various viral agents in KS and the putative role of those viruses in the pathogenesis of the disease.