Viral infections of the CNS are typically associated with mortality and morbidity. These infections are caused by a variety of both DNA and RNA viruses, and occur in individuals of all ages. Worldwide, disease burden is most frequently attributed to herpes simplex virus, varicella zoster virus, cytomegalovirus, Japanese encephalitis and measles infection of the CNS. The epidemiology and pathogenesis of these infections varies according to the organism and the locale of occurrence. Importantly, therapy has only been identified for herpes simplex encephalitis, varicella zoster virus and cytomegalovirus infections of the CNS. The utilization of aciclovir and ganciclovir will improve the morbidity and mortality for these diseases. For the other CNS viral infections for which no therapy is presently available, supportive care is essential. © 1994, Adis International Limited. All rights reserved.