We performed Le Fort III midfacial advancement with gradual distraction using internal devices on a 2-year 5-month-old boy with Crouzon's syndrome with associated severe obstructive sleep apnea. The device was not activated until 7 days after surgery, after which the distraction was initiated, 1 mm per day, and the midface was advanced 4 mm intraoperatively and distracted 12 mm postoperatively. A total advancement of 16 mm was obtained. The obstructive sleep apnea improved remarkably after the distraction. In infants and younger children with associated severe obstructive sleep apnea, advancement by distraction osteogenesis of the midface in Le Fort III maxillary osteotomy will be initially indicated to obviate tracheostomy improving the upper airway obstruction.