We report four previously healthy female children, aged between 3 and 8 years, who presented with encephalopathy and an extrapyramidal movement disorder (chorea n=4, rigidity n=2, oculogyric crisis n=2). In addition, an acute behavioural disturbance occurred in two patients and mutism in two others. Seizures heralded the onset of the illness in three patients. Acute MRI was either normal or initially normal with later generalized cerebral atrophy. All infective (including streptococcus), biochemical, and metabolic investigations were normal, although all four patients had oligoclonal bands in the (CSF) but not the serum, indicating intrathecal immunoglobulin synthesis. All four children made an apparently full recovery within four months of the onset. We suggest that these patients represent an immune-mediated movement disorder and encephalopathy syndrome.