IMPORTANCE: Computed tomographic (CT) scans are often obtained before mandibular distraction osteogenesis in patients with isolated Pierre Robin sequence. There is concern regarding the risk of radiation exposure from CT in children. OBJECTIVE: To evaluate whether preoperative CT is necessary for adequate airway, feeding, and aesthetic outcomes following mandibular distraction with external distraction devices in infants with isolated Pierre Robin sequence. DESIGN, SETTING, AND PARTICIPANTS: In a retrospective review of medical records, infants who underwent mandibular distraction between January1, 1998, and September 30, 2014, at 2 tertiary children's hospitals were identified using procedure codes. Data analysis was conducted December 1, 2014, to March 31, 2015. Fifty-two patients fit the inclusion criteria of isolated Pierre Robin sequence or Stickler syndrome, of being younger than 9 months at the time of distraction, and of use of external distractors. Forty-two of these infants did not receive preoperative CT imaging. EXPOSURE: Mandibular distraction osteogenesis for isolated Pierre Robin sequence or Stickler syndrome. MAIN OUTCOME MEASURES: Number of infants who were able toavoid tracheostomy or achieve decannulation, who were able to avoid placement or achieve removal of a gastrostomy tube, and in whom there were no intraoperative complications, no open-bite deformity, no malocclusion, no asymmetry, and no postoperative complications. RESULTS: In comparison with the 10 infants who underwent preoperative CT, all 42 of the infants (100%) who did not receive preoperative CT imaging successfully avoided tracheostomy or achieved decannulation (P =.04) and 40 patients (95%) did not require placement ofa gastrostomy tubeor were able to undergo gastrostomy tube removal postoperatively (P <.001). There were no significant differences between the CT and non-CT groups in the other 5 outcome measures. Two patients (5%) required postoperative gastrostomy tube placement, 2 patients (5%) had minor intraoperative complications that might have been anticipated with CT, 2 patients (5%) demonstrated malocclusion, and 1 infant (2%) had asymmetry at the end of the distraction phase. CONCLUSIONS AND RELEVANCE: This series suggests that the absence of preoperative CT does not compromise functional or aesthetic outcomes in mandibular distraction with external distraction devices in infants with isolated Pierre Robin sequence or Stickler syndrome. This finding has implications for cost containment and reduction of radiation exposure to a vulnerable population.