The purpose of this study was to investigate the prevalence of TMJ internal derangement, the pathologic status, and the relation of craniofacial morphology.Seventy-one patients (14 males and 57 females, mean age: 22y 0m) with jaw deformities were selected as subjects. MRI and tomogram were taken of each subject to identify the intraarticular pathologic status with reference to Wilkes/Schellhas criteria. Craniofacial morphology was analyzed by using posteroanterior and lateral cephalograms. Association between intraarticular pathologic status and craniofacial morphology was examined by means of Spearman rank correlation analysis.Internal derangement was found in 37 (52.1%) patients. In patients with unilateral TMJ internal derangement, a significantly positive correlation was found between lateral shift of the mandible and the TMJ pathologic stages. Ramus height (r=0.300, p<0.05) and maxillomandibular relation (r=0.594, P<0.01) significantly correlated with the pathologic stage of TMJ internal derangement.The results also showed a significantly positive correlation (r=0.926, p<0.05) between clockwise rotation of the mandible and the stage of TMJ internal derangement in subjects with bilateral TMJ internal derangement.These findings revealed a significant relation of mandibular or craniofacial morphology and the degree of TMJ internal derangement.