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. METHODS 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.