OBJECTIVE: Vitamin E (alpha-tocopherol), a free-radical scavenger, has been reported to improve symptoms of tardive dyskinesia. The authors attempted to replicate this finding under more controlled conditions in a larger study group. METHOD: Fifteen inpatients and six outpatients with tardive dyskinesia received up to 1600 IU/day of vitamin E for 6 weeks in a double-blind, placebo-controlled crossover study. Abnormal Involuntary Movement Scale (AIMS) examinations of these patients were videotaped and rated independently by two trained raters. Levels of neuroleptic medication and vitamin E were measured during both treatment periods. Eighteen patients who demonstrated high blood levels of vitamin E were included in the data analysis. RESULTS: Vitamin E levels were significantly higher while the patients were receiving vitamin E than while they were receiving placebo. For all 18 patients, there were no significant differences between AIMS scores after receiving vitamin E and AIMS scores after receiving placebo. In agreement with previous studies, however, the nine patients who had had tardive dyskinesia for 5 years or less had significantly lower AIMS scores after receiving vitamin E than after receiving placebo. There were no changes in neuroleptic levels during vitamin E treatment. CONCLUSIONS: Vitamin E had a minor beneficial effect on tardive dyskinesia ratings in a selected group of patients who had had tardive dyskinesia for 5 years or less. This effect was not due to an increase in blood levels of neuroleptic medications.