The primary aim of this randomized, controlled trial was to assess the effectiveness of botulinum toxin A (BoNT-A) injections into the submandibular and parotid glands on drooling in children with cerebral palsy (CP) and other neurological disorders. Secondary aims were to ascertain the duration of any such effect and the timing of maximal response. Of the 48 participants (27 males, 21 females; mean age 11y 4mo [SD 3y 3mo], range 6-18y), 31 had a diagnosis of CP and 15 had a primary intellectual disability; 27 children were non-ambulant. Twenty-four children randomized to the treatment group received 25 units of BoNT-A into each parotid and submandibular gland. Those randomized to the control group received no treatment. The degree and impact of drooling was assessed by carers using the Drooling Impact Scale questionnaire at baseline and at monthly intervals up to 6 months postinjection/baseline, and again at 1 year. Maximal response was at 1 month at which time there was a highly significant difference in the mean scores between the groups. This difference remained statistically significant at 6 months. Four children failed to respond to the injections, four had mediocre results, and 16 had good results. While the use of BoNT-A can help to manage drooling in many children with neurological disorders, further research is needed to fully understand the range of responses.