In the evaluation of the beauty and functional integrity of the lower face, the oral cavity, teeth, mandible, maxilla, and the size and position of the tongue are important. The tongue locates forward and is larger than normal in prognathism, in which the jaw protrudes from the skull. It is not clear whether an enlarged tongue causes the open bite, protrusion or dental arch misalignment, or is a result of them. Here, we report two patients with mandibular prognathism and relative macroglossia, which were treated by mandibular setback surgery using a bilateral sagittal split osteotomy (BSSO) and excision of the tongue. This procedure achieved aesthetic improvement of the face and dentition.