The genus Enterovirus is a large group of viruses belonging to the family Picornaviridae. They have a worldwide distribution, cause a wide spectrum of disease, and are a common cause of central nervous system disease. Included among the sixty-six enterovirus serotypes known to infect humans are the three poliovirus (PV) serotypes, the cause of paralytic poliomyelitis (PPM). PPM has been controlled in many parts of the world by vaccination. Molecular and functional comparison of PV vaccine strain and wild neurovirulent PV strains has provided an insight into mechanisms of neurovirulence. Enteroviruses are also the most commonly implicated viral agents of aseptic meningitis. Less commonly they cause a more serious encephalitis. Specific antiviral treatment for enterovirus infections is not currently available. Virological diagnosis is nonetheless important to distinguish between enterovirus-induced meningitis or encephalitis and other treatable causes of disease with a similar clinical picture.