BACKGROUND: Tardive dyskinesia (TD) is an infrequent but important complication of treatment with antipsychotic medications. Although newer antipsychotics may be less likely to cause TD, it still occurs among some mentally ill patients previously treated with typical antipsychotics. Although usually mild, TD may be more troublesome in some patients. There is no proven curative or suppressive treatment that is effective in all patients. Suppressive treatment with cholinergic agents derives from a hypothesized balance between dopaminergic and cholinergic neurotransmission in the extrapyramidal system. Although previous trials of cholinergic precursors have been unsuccessful in treating TD, their effect on central cholinergic neurotransmission remains uncertain in view of evidence of damage to striatal cholinergic neurons in patients with TD. In contrast, the recent development of cholinesterase inhibitors that are effective in modifying the central cholinergic deficit in Alzheimer’s disease, prompted us to investigate the therapeutic effect of galantamine in patients with TD.