Acute hemorrhagic leukoencephalitis (AHL) is a rare demyelinating disease mainly affecting children, characterized by acute onset, progressive course and high mortality. A 62-year-old man was admitted to our Unit for diplopia and ataxia ensuing 2 weeks after the onset of pneumonia. MRI T2-weighted images showed signal hyperintensities in the brainstem. Antibodies against Mycoplasma Pneumoniae and cold agglutinins were found. Two weeks later the patient had a worsening of his conditions: he developed left hemiplegia with motor focal seizures and the day after he was deeply comatose (GCS = 4). A second MRI scan showed extensive hyperintensities involving the whole right hemisphere white matter with a small parietal hemorrhagic area. The clinical and neuroimaging features suggested the diagnosis of AHL, Aciclovir in association with steroid therapy were administered and then plasmapheresis was started. After 30 days of coma, the patient gradually reacquired consciousness and motor functions; anyway a left hemiplegia persisted.