The effect of arthroscopic release of temporomandibular joint (TMJ) discs was prospectively studied using a combination of preoperative tomograms, magnetic resonance imaging (MRI) scans and arthrograms, and postoperative MRI scans. Of 92 patients studied, 60 had bilateral and 32 had unilateral joint disease. All of the 152 joints studied had anterior disc displacement preoperatively. Postoperative MRI scans revealed that 92% of the patients had persistent anterior disc displacement, although 80% of the patients did have marked improvement of disc mobility. Ninety-two percent of the total patient sample had a significant reduction in pain and restoration of normal mandibular function.