Orthognathic surgery is a common approach for treatment of maxillofacial deformities. Sagittal split ramus osteotomy (SSRO) is one of the most common techniques used to treat various mandibular deformities. A LeFort I osteotomy is suggested in deformities of the maxilla and can be used along with SSRO or intra-oral vertical ramus osteotomy (IVRO).The aim of orthognathic surgery is to improve function and facial appearance; this benefits the patient psychologically and socially. Common complications which may occur in orthognathic surgery include vascular disease, temporomandibular joints (TMJ) problems, nerve damage, infection, bone necrosis, periodontal disease, vision impairment, hearing problems, hair loss, and neuropsychiatric problems. Rarely complications could be fatal. Because of the wide range of complications the surgeon should keep prevention protocols in mind and be prepared to treat them should they occur. In this chapter, common complications of various osteotomies in the mandible and maxilla are discussed.