Down syndrome (DS) children with sleep apnea often present with oral breathing associated with nasal obstruction. This causes the oral cavity and pharynx to become dry. We describe the treatment of three DS children with sleep apnea who were treated using products for oral dryness. Snoring disappeared after treatment in two of the children and apnea disappeared in all three. The symptoms of a reddened oral mucosa and coated tongue disappeared in all three DS children. Saliva pH testing demonstrated that the pH value increased in all of the children after treatment. These results indicate that oral care can improve the oral hygiene status of DS children, and that proper oral care can help prevent oral mucosal dryness and thereby reduce sleep apnea symptoms.