Acute disseminated encephalomyelitis (ADEM) is an acute demyelinating infection of the CNS that is characterized by multifocal white matter involvement often following an infection and vaccination. A 16-year-old child receiving risperidone for 7 years for the treatment of attention-deficit/hyperactivity disorder was hospitalized with complaints of double-vision during the past month and weakness on his right side, ataxia, and vomiting over the past 3 days. The child was diagnosed with ADEM after clinical, laboratory, and cranial MRI was conducted. Following an initial 3-day therapy with pulsed methylprednisolone, the child showed obvious clinical improvement. The treatment was continued with prednisolone and significant improvement was achieved. Enterovirus was detected in the results of the viral examination of the CSF. This child was found to be an interesting case having been diagnosed with ADEM associated with enteroviral infection, because of the rarity of few case reports in the literature.