OBJECTIVE: Distraction osteogenesis is an alternative treatment method for the correction of mandibular hypoplasia. In this case report, distraction with a multidirectional extraoral device was performed to gradually lengthen the corpus and ramus of a patient who had a severe hypoplastic mandible. MATERIALS AND METHODS: The patient underwent bilateral extraoral ramus and corpus distraction osteogenesis. After seven days of latency period, distraction was performed 0.5 mm twice a day. Subsequent consolidation period was 12 weeks. RESULTS: The patient's mandible was elongated successfully. Cephalometric analysis revealed that ANB angle decreased from 13 degrees to 6 degrees , overjet of 15 mm decreased to 4 mm, corpus length increased from 49 mm to 67 mm, and ramus length increased from 41 mm to 43 mm. Posterior airway space (PAS) also increased due to advancement of the mandible. In stereolithographic model evaluation it was determined that the distances from condylion to gonion and from gonion to pogonion increased. CONCLUSION: Satisfactory results from both aesthetic and functional standpoints were obtained by distraction osteogenesis of the ramus and corpus.