Acute disseminated encephalomyelitis(ADEM) and acute relapsing disseminated encephalomyelitis(ARDEM) are representative demyelination diseases that occur among young children with a fulminant onset similar to encephalitis or meningitis. The diseases often occur after some viral infection of immunization and the etiology of these diseases is considered to be an autoimmune response because of the similarity in pathologic findings to experimental allergic encephalomyelitis. Cerebral computed tomography(CT) findings of demyelination in ADEM or ARDEM show normal to low density areas in the white matter. In cerebral MRI findings, a scattered distinct high intensity lesion considered to be demyelination is observed in 72-weighted imaging even in the early stages. ADEM is usually monophasic, but recurrent episodes may occure. When ADEM is reccurent, the distinction from multiple sclerosis becomes difficult. We report here a case of acute relapsing disseminated encephalomyelitis(ARDEM) in a 9 years old male child who experence ADEM, 3 times.