Kaposi sarcoma-associated herpesvirus (KSHV) was discovered in 1994 and is now known to be a necessary but not sufficient causative agent of Kaposi sarcoma. While KSHV is likely also the causative agent of primary effusion lymphoma and multicentric Castleman's disease, its causal role has been refuted in the case of multiple myeloma, sarcoidosis, prostate cancer, and amyotrophic lateral sclerosis. The epidemiology of KSHV is both intriguing and challenging. Two epidemiologic findings are clear, but their explanation is unknown. The first is that KSHV is distributed disparately throughout the world, with the virus being common in the general population throughout Africa and the Middle East, but uncommon virtually everywhere else. The second is that even though the virus is uncommon in the general population in industrialized settings, it is disproportionately concentrated among homosexual men in these areas. KSHV has special importance to the dental profession because saliva is the body fluid that harbors it most commonly, although exactly in which ways saliva spreads the virus are not known.