Acute disseminated encephalomyelitis is an inflammatory demyelinating disease of the central nervous system that has been associated with influenza immunization, but only a few cases related to vaccination for influenza have been reported. Acute disseminated encephalomyelitis developed in a 42-year-old woman within 3 weeks of receiving the seasonal influenza vaccine. She had 80% recovery after 3 months of treatment with methylprednisolone. Although cases of acute disseminated encephalomyelitis after vaccination for influenza are rare, enough of them have occurred that critical care nurses should be aware of the possibility. Early treatment can prevent serious residual signs and symptoms; therefore, correct and quick diagnosis is important. Medical history obtained from patients with central nervous system problems should include history of recent vaccinations. (Critical Care Nurse. 2016;36[3]:e1-e6)