The aim of this study was to determine whether botulinum toxin A (BTX-A) injected into the parotid and submandibular salivary glands of children aged 6 to 16 years with cerebral palsy (CP) and relative sialorrhoea significantly decreases their drooling and improves their quality of life. Twenty children (10 males, 10 females; mean age 10y 1mo [SD 3y 8mo]; range 6y 1mo-16y 7mo) with CP, identified as having significant daily drooling (scoring at least 6 on drooling frequency/severity scales) were recruited. BTX-A (2U/kg; maximum 70U) was injected under sedation, using ultrasound guidance (1.4U/kg and 0.6U/kg divided between parotid and submandibular glands respectively). Nineteen children completed the study: 15 with spastic quadriplegia (Gross Motor Function Classification System [GMFCS] Level V); one with dystonia (GMFCS Level V); one with hemiplegia (GMFCS Level II); and two with a mixed pattern of CP (GMFCS Levels III and V). Drooling was assessed by five methods at baseline, and 4 and 12 weeks after injection. Qualitative assessment of drooling frequency and severity scores showed statistically significant reductions at 4 weeks (p<0.001) and 12 weeks (p=0.006). Qualitative assessment of quality of life scores (rated by parents and teachers separately) also significantly improved (p<0.001 and p=0.023 respectively). Quantitative assessments showed that the number of bibs/scarves changed per day was significantly reduced at 4 weeks (p<0.001). There was no side effect from the injections themselves; 89% of parents and children wished for further intrasalivary BTX-A injections in the future. We conclude that percutaneous intrasalivary BTX-A injections into the parotid and submandibular salivary glands can reduce drooling in children with CP and relative sialorrhoea, leading to an improvement in their quality of life.