We report on the maxillofacial growth in two patients with Pierre Robin Sequence (PRS) who received mandibular distraction osteogenesis (MDO) in infancy. Bilateral MDO was performed at 9 months of age in patient 1 and at 7 months of age in patient 2. The mandible was bilaterally lengthened by 15 mm (patient 1) and 18 mm (patient 2). Computed tomography was performed before distraction and every year after MDO. Distance/angle measurements and morphological/functional assessments were performed using three-dimensional Multi-Planar Reforming images from the data of Digital Imaging and Communication in Medicine (DICOM). In distance/angle analysis, growth of the mandible as well as the maxilla and cranial base was confirmed. The enlarged upper airway was maintained without apnea symptoms. Morphological assessments showed that the temporomandibular joints were free of damage, and the permanent molars were formed normally. Early MDO was considered a useful option for improving severe airway obstruction in babies with PRS.