We studied eight patients with different types of dystonia by administering agonists and antagonists of acetylcholine (ACh) and dopamine (DA). In all seven patients who received physostigmine, there was an exacerbation of the dystonia. All six patients who received anticholinergic agents improved, as did five of eight who received bromocriptine. Neuroleptics worsened symptoms in four patients with generalized dystonia and improved symptoms in one patient with Meige syndrome. Our results suggest that DA-ACh imbalance may underlie the pathophysiology of dystonia in some patients and that bromocriptine may be effective in treating these patients.