We experienced a case of acute necrotizing encephalopathy of childhood with a good outcome. The disease continued for about three weeks, and the patient recovered with a sequela of mild left-hemiparesis. On the brain magnetic resonance imaging, abnormal intensity areas in the thalamus and putamen reduced size at an early stage of the disease. After 1 year, his mental and motor development seemed to be almost normal, but brain single photon emission computed tomography and electroencephalography were abnormal. Subclinical functional abnormalities persisted longer than had been expected.