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Macrostomia is a rare and debilitating congenital anomaly with incompletely understood etiopathogenesis. Despite the phenotypic variability in macrostomia, plastic surgeons should demonstrate competence in the diagnosis and management of this condition. The anatomy, embryology, classification, and clinical presentation of macrostomia are reviewed in this manuscript. A historical overview of surgical repair is presented that forms the basis for understanding modern techniques of repair. Finally, an effective method of macrostomia repair is presented along with review of 5-year results. It is our intent that this guide serve as a reference for plastic and reconstructive surgeons to accomplish safe, functional, and aesthetic macrostomia reconstruction.