<p>Fibrous dysplasia (FD) is a bone lesion characterized by replacement of the normal bone structure with fibro-osseous connective tissue. Maxillofacial FD causes facial asymmetry. However, reduction surgery via an intraoral approach is very challenging and can provide insufficient results. We report navigation-guided bone reduction surgery for maxillary FD and obtained favorable results. A 23-year-old man with FD of the maxilla underwent bone reduction surgery using a navigation system after preoperative planning including the mirroring method. The patient could obtain facial symmetry after surgery, and there was no facial asymmetry 9 years 3 months after surgery.</p>