Tardive dyskinesia (TD), a form of movement disorder, remains a problem for some patients who received antipsychotic medications. Increasing evidence suggests that TD may result from antipsychotic-induced dysfunction in striatal cholinergic neurons. To test whether cholinesterase inhibitors compensate for diminished cholinergic activity underlying TD, we conducted a 30-week randomized, double-blind, placebo-controlled crossover study of galantamine in 36 patients with TD.