Acute necrotizing encephalopathy (ANE) may be suspected when a young child presents with abrupt onset of altered mental status, seizures, or both. Definitive clinical diagnosis is based on magnetic resonance imaging (MRI) results. ANE is associated with influenza virus infections. Preliminary data suggests that up to 25% of ANE patients die, and up to 25% of ANE survivors develop substantial neurologic sequelae. Here, we describe a case of a comatose 22-month-old girl who was admitted to our hospital because of febrile illness and seizures. On day 13 of her illness, she died from ANE associated with infection from parainfluenza virus. Brain MRI results indicated diffuse bilateral symmetric signal changes in both basal ganglia, thalami, periventricular white matter, pons, and cerebral white matter, as well as generalized swelling of the brain.