Ten female patients with an age range of 18-40 years old with unilateral anterior discdisplacement without reduction who failed to respond to conservative lines of treatmentfor the management of TMJ internal derangement performed the pterygoid disjunctionprocedure. The rationale of the pterygoid disjunction technique can be explained aswhen the pterygoid plates are separated from the maxilla and pushed posteriorly, thepterygoid muscles pull the plates backward and inferiorly. As a result, the lateral andmedial pterygoid muscles, especially the fibers attached to the pterygoid plates, areshortened. This will (1) reduce the spasm and strain on both pterygoid muscles, (2)reduce the protractive force on the condyle, (3) reduce the upward pull on the condyle,and (4) increase the joint space. Because both the upward and anterior pull on thecondyle is reduced (by shortening the pterygoid muscles), the pressure on the posteriorbilaminar tissue (which wedges between the condyle and the posterior slope of thearticular eminence in the internal derangement) is reduced, resulting in relief of pain.Because the anterior pull on the disk condyle complex is reduced together with theincrease in joint space obtained there is a better chance for the marginally displaced diskto go back to its normal position. At the end of follow up period, all the cases showednormal range of mandibular movement, complete relieve of muscle pain and no pain onmandibular movement. Only four cases had obtained smooth jaw movement withoutTMJ sounds while tenderness in TMJ on palpation was relieved in eight cases.According to Helkimo dysfunction index, although all the cases were in severe TMJdysfunction “DiIII” preoperatively, four cases were clinically asymptomatic “Dio”, fivecases were in mild dysfunction “DiI” and one case was in moderate dysfunction “DiII”at the end of follow up period. Comparing the preoperative and the 24 weekspostoperative MRI’s of all the patients in closed mouth positions, the disc movedbackward to a more favorable position with only mild displacement.