Purpose: The purpose of this paper is to show that gap arthroplasty improve mouth opening when treating TMJ ankylosis. Patients and methods: Eight patients with TMJ ankylosis were treated by gap arthroplasty. The patients were evaluated by at least twenty-four months (minimum 24 and maximum 48 months). Results: Of the eight patients (eleven joints), five (62.5%) had unilateral involvement and three patients (37.5%) had bilateral involvement. The mean age was 20 years ± 9 (range 3 to 30 years). The mean maximal incisal opening (MIO) in the preoperative period was 9.25 ± 6.41 mm and in the postoperative period it was 29.88± 4.16 mm. The complication of temporary facial nerve paresis was encountered in two patients (25%). No recurrence was observed in our series. Conclusions: Trauma was the major cause of tempomandibular joint ankylosis in our sample. Gap arthroplasty showed good results when treating TMJ ankylosis.