Acute necrotizing encephalopathy of childhood is a rare form of acute encephalopathy of unknown etiology characterized by typical symmetrical lesions in the thalami, with variable involvement of the white matter, brainstem and cerebellum. Clinically there is a rapid neurologic deterioration after a short period of a nonspecific viral-like illness associated with gastrointestinal or respiratory signs. Asian children are especially affected. Here we present a 3-yearold boy admitted to our hospital with fever and deterioration of consciousness. His nasopharyngeal swab for polymerase chain reaction revealed positive results for human parainfluenza 2 virüs. The diagnosis of acute necrotizing encephalopathy was made by cranial magnetic resonance imaging findings with symmetrical expansile hyperintense signals in bilateral thalami.