Mandibular prognathism is a developmental dentofacial deformity, which is characterized by skeletal class III malocclusion and either excessive antero-posterior mandibular growth or relatively insufficient growth of the maxilla. Bilateral sagittal split osteotomy is the most frequently performed surgical procedure for mandibular advancement in the treatment of mandibular prognathism or retrognathism. Here we present a case of 21 years old male diagnosed with mandibular prognathism and initially treated with orthodontic intervention but cephalometric for orthognathic surgery (COGS) analysis determined surgical treatment bilateral sagittal split osteotomy under general anesthesia.