PURPOSE: The aim of this study was to evaluate the data of 11 patients who had excessive drooling attributable to various diseases such as hypoxic ischemic encephalopathy, spinal muscular atrophy, and esophageal stricture treated with the injection of botulinum toxin A. METHODS: Eleven children with excessive drooling were enrolled in a retrospective clinical evaluation. Eighty to a hundred units of botulinum toxin A were injected into the patients' parotids, submandibular glands under sonographic guide. Subjective measures including Teacher Drooling Scale(TDS) by the patients' parents or caregivers were used to determine the effect of botulinum toxin A on drooling and to document the severity and frequency of children's drooling. RESULTS: The TDS and number of suctions per day demonstrated a significant reduction at 1 week, 1 month, and 3 months in most of the patients. We defined a 2 point decrease on the TDS as "success to therapy". Five of the eleven patients(45.5%) responded to botulinum toxin A injections. Of children who responded, the definite reduction of drooling was noticed at 4 weeks after the injections in three children, at 12 weeks in one, and at 1 week in the other. No adverse effects were observed during and after the injections in this study. CONCLUSION: Parotid and submandibular botulinum toxin A injection is an effective method for the reduction of excessive drooling, demonstrating a high response rate up to 12 weeks. The procedure is simple to perform, and safe when ultrasonographic guidance is used.