Most of the world's population is eventually infected with herpes simplex virus type 1, type 2, or both. Most infected persons harbor latent virus in nerve ganglia for the rest of their lives. True primary infections, nonprimary first-episode infections, and recurrent infections can be asymptomatic or clinical, but all of these are contagious. Past estimates of recurrent herpes affecting 20% to 40% of the population are probably low because of inadequate studies of asymptomatic shedding and genital recurrences. Herpes infections are spread primarily by close personal contact but some are contracted by fomites and medical-dental procedures. Latent virus harbored by almost everyone with frequent reactivation to produce symptomatic or asymptomatic, infectious recurrent disease poses a huge problem for control or eradication of herpes simplex infections. Public health measures will probably fail because they require too much alteration of the public's life-styles. So far, antiviral drugs do not eliminate latent virus from infected ganglia. That naturally infected persons can be reinfected, superinfected, or autoinoculated raises serious questions whether vaccines will eradicate the disease, although they might control some serious manifestations and limit some spreading. The problem of eradicating herpes is different from that of eradicating smallpox, where latent infections with infectious recurrences did not exist.