Presents the results of an expert evaluation of the carcinogenic risk to humans posed by infection with two lymphotropic herpesviruses: Epstein-Barr virus and Kaposi's sarcoma herpesvirus/human herpesvirus 8, a new human herpesvirus detected in 1994 in Kaposi's sarcoma associated with AIDS. The viruses are evaluated in separate monographs, which consider the biology of the virus, the epidemiology of infections, related animal viruses, and mechanistic studies in addition to abundant studies of cancer in humans.