 Method: A double blind, randomised, placebo-controlled cross-over trial of the muscarinic antagonist, ipratropium bromide in patients with bothersome drooling in idiopathic Parkinsons disease. All patients are recruited from the Movement Disorders Clinic, Toronto Western Hospital and informed consent is obtained. Patients are randomised to receive ipratropium bromide, 1- 2 metered doses sprays of active drug 21 g per metered dose or matching placebo, up to a maximum of 4 times per day, in a double-blind, cross-over design using randomisation tables. Total treatment length is two weeks for each limb of the study with a 1-2 week wash out period. The primary outcome measure is an objective measure of saliva production. Dental rolls are inserted into the mouth for 5 min and the patient instructed not to swallow and sit upright. The weight of dental rolls before and after insertion is calculated as a measure of saliva production. The secondary outcome measures are subjective measure of saliva where patients or caregivers record the level of saliva production each day for the 2 weeks of each treatment using validated subjective rating scales which assess drooling severity and frequency. In addition, parkinsonism is rated using the UPDRS parts I IV and adverse events are recorded. The scores for measured saliva production following ipratropium bromide and placebo treatment will be compared using appropriate paired t-tests. Results from the scales assessing the subjective measures of saliva production and UPDRS ratings will be compared via paired non-parametric Wilcoxon matched pairs test. 20 patients will be recruited. 