Sialorrhea is a relatively common symptom in idiopathic Parkinson's disease and related conditions for which most of the accepted treatments are either highly invasive or may cause substantial systemic side effects. This study describes an open-label pilot study of sublingual atropine drops for the treatment of sialorrhea in 7 patients (6 with Parkinson's disease, 1 with progressive supranuclear palsy). Participants demonstrated statistically significant declines in saliva production, both objectively and subjectively. Self-reported drooling severity showed a significant decline between baseline and 180 minutes, t(6) = 3.240 P < 0.025 (eta(2) = 0.636), and between baseline and 1 week, t(6) = 4.583 P < 0.005 (eta(2) = 0.778). Objectively measured saliva production decreased significantly between baseline and the 1-week follow-up, t(6) = 2.711 P < 0.05 (eta(2) = 0.551). Delirium occurred in 1 patient (concurrent with a urinary tract infection), and 2 patients experienced worsening of hallucinations (active hallucinosis was concealed by both individuals to allow participation in the trial). The remaining trial participants did not experience any anticholinergic side effects. This trial shows that, in selected patient populations, sublingual atropine is a simple and inexpensive treatment for sialorrhea associated with parkinsonism.