Treacher-Collins syndrome usually affects bilateral and symmetric structures that include the orbits, zygomatic complex, mandible, and ears. The purpose of this report is to describe a clinical case of the syndrome, focusing on the temporomandibular joint (TMJ). A 33 year-old male presented to our department with severe mouth opening limitation, he had never been treated for his condition. Midfacial hypoplasia with a bilaterally symmetric convex facial profile, prominent nose, downward slant of the eyelids, sparse lower eyelashes and small ears were present. Family history was consistent with autosomal dominant inheritance. He had hypoplasia of the maxilla and mandible with uncharacteristic posterior open bite and severe mouth opening limitation (<5 mm), CT scan revealed abnormal bilateral ankylosis between a hyperplasic zygomatic arch and the mandibular condyle. We performed surgical excision of the ankylosis (lateral aspect of the zygomatic and condyle) preserving the medial portion of the condyle, coronoidectomy and on lay malar bone graft with the excised bone. Mouth opening greatly improved with the procedure (20 mm). Most cases of TCS present with underdeveloped zygomatic arch. We report a case of ankylosis between a hyperplasic zygomatic arch and the condyle of the mandible, successfully treated with excision of the ankylosis.