Measles is a highly contagious viral disease caused by an enveloped negative-strand RNA virus in the Paramyxovirus family. Measles is associated with three different types of neurologic complications: acute disseminated encephalomyelitis (ADEM), measles inclusion body encephalitis (MIBE), and subacute sclerosing panencephalitis (SSPE). ADEM is a monophasic autoimmune demyelinating disease that has an incidence of 1:1000 and occurs primarily in children over the age of 4 years. Disease onset is acute and usually occurs within days to weeks after measles. Pathology is characterized by perivenular inflammation and demyelination. MIBE is due to progressive measles virus infection of the nervous system and occurs in immune-compromised individuals who are unable to clear virus after infection. Disease onset is subacute and usually fatal. Pathology shows nuclear and cytoplasmic viral inclusion bodies with little evidence of inflammation. SSPE is a fatal progressive neurologic disease with an onset many years after measles and an incidence of 1:10. 000. The disease occurs primarily in immunologically normal children who developed measles under the age of 2 years. Pathology shows nuclear and cytoplasmic inclusion bodies and inflammation. All of these diseases can be prevented by measles vaccination.