In 103 patients (mean age 9 years) with the pauciarticular or polyarticular type of juvenile rheumatoid arthritis, clinical aspects of mandibular growth and function and general disease variables were correlated with radiographically observed temporomandibular joint (TMJ) abnormality. Discriminant analysis of the entire group revealed that a combination of disease duration and disease activity was associated with TMJ abnormality; however, a correct classification of the TMJ condition could be made in only 63 patients (63%). Further analyses revealed three effective indicators of TMJ arthritis: reduced maximal mouth opening capacity, vertical difference between the two mandibular angular regions, and deviation of the mandible at maximal protrusion. A combination of these variables discriminated correctly between the presence or absence of TMJ abnormality in 52 of a subgroup of 56 patients (93%).