Acute disseminated encephalomyelitis is a type of post-infectious encephalomyelitis that occurs mostly in children and occasionally in adults. We report the case of a 3-year 5-month-old girl with bronchopneumonia and acute otitis media. She had neurological symptoms including bilateral leg weakness, right arm weakness, pain, and neck stiffness after defervescence of fever. Brain and spinal T2-weighted flair magnetic resonance images revealed multifocal demyelinating lesions with variable enhancement within the white and gray matter of cerebral hemispheres, cerebellum, brainstem, and spinal cord. The diagnosis of acute disseminated encephalomyelitis was made. Her neurological symptoms gradually improved two weeks after administration of intravenous immunoglobulin 0.5 g/kg/day for two days. Six months later, follow-up T2-weighted flair magnetic resonance images showed resolution of the demyelinating lesions in the brain parenchyma. We report a rare case of a little girl with acute disseminated encephalomyelitis.