Dr Lang's observations warrant a randomized, double-blind, placebo-controlled trial of domperidone in patients starting agonist treatment to test if orthostatic hypotension can be avoided. Since the drug is not easily available in the United States, the natural place to conduct this study in North America would be Canada. Because of the frequency of orthostatic hypotension in our study, only a moderate number of patients would need to be enrolled to settle this question. In an era increasingly conscious of evidence-based medicine, a study of this type would offer "level 1" data on the treatment of drug-induced dysautonomia in patients with Parkinson's disease.