Classification, structure and characteristics of neurotropic viruses are briefly summarized. Neurotropic viruses causing acute infection include Japanese, Venezuelan equine, and California encephalitis viruses, polio, coxsackie, echo, mumps, measles, influenza, and rabies viruses as well as members of the family Herpesviridae such as herpes simplex, varicella-zoster, cytomegalo and Epstein-Barr viruses. Those causing latent infection include herpes simplex and varicella-zoster viruses. Those causing slow virus infection include measles, rubella and JC viruses, and retroviruses such as human T-lymphotropic virus 1 and human immunodeficiency virus. Prion, which is not a virus but a host-derived non-physiological protein, causes transmissible spongiform encephalopathy such as kuru and Creutzfeldt-Jakob disease that resemble slow virus infection.