Temporomandibular joint ankylosis may be true or false. Most commonly, trauma and inflammatory conditions lead to this condition. Zygomatico-coronoid ankylosis is a rare extra-articular (false) form of ankylosis of the jaw. This condition may follow treated or untreated midface fractures. Coronoid process locking may be overlooked because attention is generally focused on temporomandibular joint. A review of literature has reported 16 cases of this disorder. The true incidence of this condition may be even higher. In this paper, we present an unusual case of posttraumatic bony ankylosis of the right coronoid process of the mandible with the zygomatic arch in a 30-year-old male. This bony ankylosis was produced by a mass of heterotopic bone formed, following inadequate treatment of midfacial fracture. Extra-oral ostectomy of the ankylotic mass followed by immediate postsurgical aggressive physiotherapy produced good long-term functional outcome.