Background: - Temporomandibular joint ankylosis is fusion of the head of mandibular condylernto the glenoid fossa of temporal bone. Untreated ankylosis causes distressing conditions such asrnspeech impairment, difficulty in chewing, poor oral hygiene, malocclusion, facial disfigurement,rnand compromise of the airway (tongue fall in sleep) especially in bilateral involvement withrnsevere micrognathia. The two main cause are trauma and infection in or around the joint regions. rnObjectives: - The aim of this study was to assess the pattern, aetiology and treatment ofrntemporomandibular joint ankylosis at Addis Ababa University Oral and Maxillofacial surgeryrnaffiliate Hospitals. rnMaterials and Methods: - A retrospective cross sectional study was conducted in 25 patientsrn(n=14 male and n=11 female) with mean age of 21.9(ranged 6-50) diagnosed withrnTemporomandibular joint ankylosis at Addis Ababa University, Oral and Maxillofacial Surgeryrnaffiliate Hospitals both Yekatit 12 Hospital medical college and St. Peter specialized Hospital.rnData was collected from patientsâ€™ medical records registered in a period of 3 years from Januaryrn2017 to December 2019. EPI- INFO 7 computer software was used for data analysis. rnResults: - The study results revealed trauma was the most common cause of TMJ ankylosisrnrepresenting (80%) of all causes. Males were more affected (56%) than females. The highestrnincidence of ankylosis was between the age of 11 and 20 (40%). Unilateral ankylosis wasrnreported in (60%) and (68%) was bony ankylosis based on tissue involved. A total of (40%) ofrnthe patients were treated by interpositional gap arthroplasty by using temporal muscle and fasciarnas an interpositional material. Tracheostomy was used as intubation technique and securing thernairway in majority (77 %) of patients. rnConclusion: - The findings of this study conclude trauma was the commonest cause ofrnankylosis. Unilateral ankylosis based on side of affected and bony ankylosis based on tissuerninvolved was the most common type of temporomandibular joint ankylosis. A proper screeningrnof childhood injuries and early referral to maxillofacial centers recommended ensuring properrnevaluation of specific post traumatic aetiologic factors and for early treatment to preventrnankylosis and associated growth deformities. Tracheostomy was the most commonly usedrnintubation technique, where fiberoptic intubation facility unavailable. Institutional capacityrnbuilding of facilities, increasing service availability and experts for practice of fiberopticrnintubation technique recommended.