Drooling is a common and incapacitating problem in Parkinson's disease (PD). Treatment with botulinum neurotoxin (BoNT) into the parotid glands seems beneficial. Injection of the submandibular glands may also be effective since these produce 70% of the daily unstimulated saliva. We randomly allocated patients to BoNT injections into the submandibular glands or the parotid glands. Within-group improvements were significant for the submandibular group, but not for the parotid group. Between-group differences showed a trend towards superiority for the submandibular group. Injecting the submandibular glands instead of the parotid glands seems a promising approach, and larger studies are justified.