Acute disseminated encephalomyelitis (ADEM) is an immune-mediated inflammatory paediatric disorder of the central nervous system (CNS). ADEM primarily affects the white matter of the brain and spinal cord. The aetiology of ADEM is unknown, but the illness is often precipitated by an infection, less often by vaccination. ADEM is characterized by acute polyfocal CNS deficit, including encephalopathy. This can be seen on MRI as simultaneously occurring multifocal lesions. Empirical treatment with steroids or immunoglobulins is often used. The prognosis of ADEM is usually favourable. This article describes two Danish cases both demonstrating trait characteristics of ADEM as well as the importance of an MRI considering an ADEM diagnosis early in the course of the illness.