Four patients with temporomandibular joint ankylosis, three bilateral, one unilateral, were treated successfully by using the technique of silicone cap arthroplasty. Among these patients two were recurrent cases. Mean maximum incisal opening distance was 6.0 mm preopera tively and 24.7 mm postoperatively. In the follow-up period ranging between 19 months and 5 years, all of the patients had satisfactory mouth opening for chewing and speaking without any reankylosis. We believe that the silicone cap provides a satisfactory range of motion and prevents cortical callus formation across the cap by wrapping around the mandibular stump: this reduces the risk of reankylosis. The simplicity and the short duration of the operation as well as the nonexistence of an additional scar are other reasons for preferring this method. Furthermore, the silicone cap arthroplasty technique has the advantage of controlling the amount of bone removal thus decreasing the risk of the development of a short ramus.