OBJECTIVE: Tetrabenazine, a monoamine depleter and dopamine receptor blocker, is used to treat several hyperkinetic movement disorders. The authors studied the use of tetrabenazine for tardive dyskinesia. METHOD: Twenty patients with tardive dyskinesia (mean duration=43.7 months) were videotaped before and after tetrabenazine treatment. Randomized videotapes were scored with the motor subset of the modified Abnormal Involuntary Movement Scale (AIMS) by raters blind to pre- or posttreatment status. RESULTS: One patient did not tolerate tetrabenazine owing to sedation. The remaining 19 were rated after a mean of 20.3 weeks at a mean tetrabenazine dose of 57.9 mg/day. There were significant improvements in mean scores on both the patient AIMS self-rating and the AIMS motor subset evaluated by the blind videotape raters. All 19 patients continued to take tetrabenazine after the study. CONCLUSIONS: Tetrabenazine was well tolerated and resulted in significant improvements in AIMS scores for patients with refractory tardive dyskinesia.