Subacute sclerosing panencephalitis (SSPE) is a progressive inflammatory disease of the central nervous system (CNS) caused by a persistent, aberrant measles virus infection. The outcome is usually fatal. After a latent period of 6 to 7 years, there is subtle and slow cognitive decline and visuospatial disorientation develops followed by myoclonic jerks, extrapyramidal symptoms, ataxia, and seizures, progressing to coma or vegetative state. The diagnosis is based on at least three of the following criteria 1) clinical manifestations 2) abnormal EEG 3) hyperglobulinorrachia, elevated serum or spinal fluid measles antibody 4) histologic features. No therapeutic maneuver has been proven conclusively to be of value. We have diagnosed and experienced a case of subacute sclerosing panencephalitis (SSPE) in a 5-year-old child with the chief complaint of myoclonic seizure and mental deterioration. We report a case and the brief review of related literature.