Background: Temporomandibular joint ankylosis is the fusion of mandibular condyle to the glenoid fossa, which causes distressing conditions. It may be due to trauma or infection. The aim of this study is to determine the frequency of TMJ Ankylosis in Khartoum teaching dental hospital among children. Materials and methods:A retrospective cross sectional study for 48 patients (32 male, 16 female) aged 0-18 years old. Data were collected from patients records registered from January 2009 to April 2015.Results: Males were more affected than females, the most affected age group was 7-12 years old, bilateral ankylosis more common than unilateral, intra capsular ankylosis is the most common type, and micrognathia is the most common deformity. 41 patients received treatment, coronoidectomy with condylectomy and physiotherapy is the most preferable treatment method. Also Condylectomy + Gap arthroplasty + Physiotherapy and Gap arthroplasty + Coronoidectomy + Physiotherapy were used. In some cases physiotherapy overcome the ankylosis, and only 7 patients didn't receive any type of treatment. Conclusion:The prevalence of TMJ ankylosis among children was high; the most common causes were trauma and infection, whereas most of patients came with intracapsular type ankylosis in children leads to facial deformities. Improvement of awareness regarding condyle fracture is required. TMJ Ankylosis is fusion of the mandibular condyle to the glenoid fossa in the base of the skull, which causes distressing conditions such as impaired speech, difficulty in chewing, poor oral hygiene, facial disfigurement, compromise of the airway, and psychological stress [2].Various etiological factors had been attributed to TMJ ankylosis; trauma, local and systemic inflammatory conditions, neoplasm, and TMJ infection. The most frequent one trauma and infection [3].Fractures of the condylar head are more prone to postoperative ankylosis of the TMJ, and that the possible risk factors seem to include the technique used for fixation and damage to the disc, together with an anterior mandibular fracture and with the remaining fractured fragment [4]. Bilateral TMJ ankylosis caused by systemic infection is reported [4]. The clinical findings of TMJ ankylosis in children in unilateral ankylosis reveal unilateral hypoplasia of the mandible and deviation of the chin to the affected side. Bilateral ankylosis results in bird-face appearance; night snoring and obstructive sleep apneas are the other clinical findings in bilateral ankylosis [5]. Later joint involvement after 15 years of facial deformity is marginal or nil but functional loss is severe [6].TMJ imaging comprise; plain radiography, panoramic radiography, tomograms, conventional CT, arthrography, three dimensional CT, magnetic resonance imaging, ultrasonography, and radionuclide imaging [7,8].The management goal in TMJ ankylosis is removal of the ankylotic mass, restoring the form and function of the joint, mouth opening, relief of upper airway obstruction, and prevention of recurrence [9].A numb...