- OBJECTIVE: The authors' goal was to conduct a double-blind trial of vitamin B6 in the treatment of tardive dyskinesia in patients with schizophrenia. METHOD: Fifteen inpatients with schizophrenia who met research diagnostic criteria for tardive dyskinesia were randomly assigned to treatment with either vitamin B6 or placebo for 4 weeks in a double- blind crossover paradigm. The Extrapyramidal Symptom Rating Scale was used to assess patients weekly. RESULTS: Mean scores on the parkinsonism and dyskinetic movement subscales of the Extrapyramidal Symptom Rating Scale were significantly better in the third week of treatment with vitamin B6 than during the placebo period. CONCLUSIONS: Vitamin B6 appears to be effective in reducing symptoms of tardive dyskinesia.