Temporomandibular joint internal derangement (TMJ ID) is the most common intra-articular TM disorder and can progress from TMJ ID with reduction to TMJ ID without reduction. It is not known whether this anatomical progression is associated with increasing levels of mandibular dysfunction. The objective of this study was to determine whether the level of clinically detectable mandibular dysfunction was related to the stage of TMJ ID. Two clinicians examined 42 subjects prior to bilateral TMJ arthrographic evaluation. The level of mandibular dysfunction was calculated by Helkimo's Clinical Dysfunction Index (Di) and the Craniomandibular Index (CMI). Statistical analysis revealed that the level of mandibular dysfunction as determined by the Di and CMI was not related to the arthrographic presence or absence of TMJ ID. Therefore, the clinician cannot assume that the level of mandibular dysfunction is directly related to the absence or presence of TMJ ID. Epidemiologically, the CMI and Di can be used only for estimation of the degree of mandibular dysfunction, since they do not provide direct information on a specific TM disorder.