The effects of vagal nerve stimulation on sleep-related breathing have not been well-described in children. Vagal nerve stimulation was reported to cause decreases in airflow during sleep, although most studies reported this condition to be clinically insignificant. We present a retrospective case series of nine children who underwent polysomnography after vagal nerve-stimulator placement. All children, except for one, had sleep-disordered breathing after stimulator implantation. We describe in further detail a child who manifested severe, obstructive sleep apnea postimplantation, with apneas occurring regularly and consistently with stimulator activity, resulting in an elevated apnea-hypopnea index of 37 per hour. Polysomnography was repeated with the stimulator turned off, and revealed complete resolution of the stimulator-related sleep apnea. With the vagal nerve stimulator back on, continuous positive airway pressure treatment was effective in normalizing the apnea-hypopnea index. This study demonstrates that severe and clinically significant disturbances in sleep-related breathing may occur with vagal nerve stimulators. Obstructive apneas of this severity, related to vagal nerve stimulators, were not previously described in pediatric patients. This effect on sleep-related breathing warrants further investigation and care in managing pediatric patients.