The case of a 12-year-old girl with the typical clinical symptoms of the recently described anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is reported. Within 6 weeks the full clinical spectrum of this condition presented with seizures, agitation, stupor, autonomic instability, dysphagia and hypoventilation leading to a diagnosis of pernicious catatonia. MRI and CSF glucose, protein and lactate were repeatedly normal. EEG revealed rhythmical slowing. No teratoma was detected. Recognition of the unique pattern of the clinical symptoms led to early consideration of this disease which was confirmed by detection of anti-NMDAR antibodies. After high dose prednisolone without clinical improvement, plasmapheresis was followed by a rapid reduction in antibodies and recovery within a few weeks. To our knowledge this is the youngest patient with anti-NMDAR encephalitis to have been described to date. We speculate that NMDAR antibodies may be directly involved in the pathogenesis of this disease.