The predictive value of radiographic tomoraphy was assessed using magnetic resonance imaging as a definitive test of TMJ soft-tissue status in a predominantly asymptomatic adolescent sample. Eighty-two TMJs in 41 subjects (mean age = 12.5 years, range = 10 to 17 years) were independently evaluated using axially corrected tomography and magnetic resonance imaging. Tests of comparison and correlation were performed. Correspondence of tomographic classifciation to magentic resonance imaging classification on nondisplacement (55%), reducing internal derangement (35%), or nonreducing internal derangement (10%) showed a significant relationship (P .05). Tomography as a diagnostic test of abnormal disc position had a sensitivity of 0.43, a specificity of 0.80, a positive predictive value of 0.64, and a negative predictive value of 0.63. Tomography is inappropriate as a diagnostic test for TMJ internal derangement.