Tardive dystonia in a chronic dystonia caused by neuroleptics. A 53-year-old man suffering from a neuroleptic induced dyskinesia began to show an abnormal posture. His abnormal posture was caused by changes of muscle tonus and thought to be a dystonic posture. He had no family history of dystonia. This posture was similar to that of idiopathic dystonia in that the muscle tonus was hypertonic in sitting but was hypotonic in lying, and in that the activity of daily living was not disturbed in spite of hypertonia. But he also showed lingual dyskinesia and hyperreflexia and the electromyographic analysis disclosed the fact that his dystonia was similar to that of secondary dystonia. Brain CT showed the atrophy of the head of caudate nucleus but superconducting MRI disclosed no abnormality in basal ganglia. No effective therapeutics was as yet found in tardive dystonia. So it was proposed that the tardive dystonia was due to irreversible functional damage to the basal ganglia.