This retrospective study of nine cases of TMJ Ankylosis evaluated the postoperative results of interpositional arthroplasty on temporalis muscle and fascia flap in adults. The operative protocol for unilateral TMJ ankylosis entailed (1) resection of ankylotic mass, (2) intraoral ipsilateral coronoidectomy, (3) contralateral coronoidectomy when necessary, (4) interpositional tissue transfer to the TMJ with temporalis muscle, fascia flap, and (5) early mobilization, aggressive physiotherapy. The study evaluated nine patients with follow-up checks from 13 to 31 months (mean 18.3 months). Patients had a preoperative maximal interincisal opening of 9–19 mm (mean 11.7 mm). During the last follow-up observation after surgery, the patients had a maximal interincisal opening of 35–40 mm (mean 38.3 mm).The results of this protocol were encouraging, the functional results of interpositional arthroplasty on temporalis muscle and fascia flap were also satisfactory. The findings of this study support the use of temporalis muscle and fascia flap in adult patients with unilateral TMJ ankylosis. Early postoperative initial exercise, physiotherapy and strict follow-up play an important role.