Subacute sclerosing panencephalitis (SSPE) is a subacute encephalopathy of childhood and young adolescence. Infrequently, SSPE can occur in adults and pregnant women. It is caused by an aberrant measles virus, known as the SSPE virus. SSPE virus differs from wild-type measles viruses in the form of several mutations affecting the viral genome. The matrix gene is most commonly affected by these mutations. The characteristic clinical manifestations of SSPE include behavioral changes, cognitive decline, myoclonic jerks, seizures, abnormalities in vision, bilateral pyramidal signs and coma. Ocular changes may occur in up to 50 % of patients. The most characteristic ophthalmological lesion is necrotizing retinitis. Cortical blindness can be the early feature of SSPE. The diagnosis of SSPE is often difficult in the early stages. In a typical case diagnosis is based on clinical, electroencephalographic, and cerebrospinal fluid findings. At present, there is no effective treatment to completely cure SSPE. Oral isoprinosine and intrathecal or intraventricular alpha-interferon may prolong survival to some extent. Immunization against measles is currently the most effective strategy against SSPE.