We report a case of a 5-year-old boy with acute disseminated encephalomyelitis as the initial presentation of neuroborreliosis. Parents report an upper-airway infection a few days before the development of acute encephalopathy, mild facial palsy, and seizures. The patient needed mechanical ventilation for 10 days, and after extubation, he presented hypotonia, ataxia, dysarthria, as well as weak gag and cough reflexes. Brain magnetic resonance imaging showed hyperintense lesions on T2- and fluid-attenuated inversion recovery sequences on the right subcortical occipital and parietal region, left posterior arm of the internal capsule, and in the medulla oblongata. Borrelia burgdorferi was identified in the plasma and cerebrospinal fluid by polymerase chain reaction and in the plasma by Western blotting. He was treated with ceftriaxone, methylprednisolone, and human immunoglobulin. Recovery was partial.