Thirty-six temporomandibular joints (TMJs) in 28 symptomatic patients (aged 14-40 years) with rheumatic disease (mostly rheumatoid arthritis) were studied with magnetic resonance (MR) imaging and hypocycloidal tomography. MR images of four TMJs were normal. Another four TMJs showed internal derangement. Of the 28 TMJs presumed to show rheumatic disease involvement (26 with condylar destruction or deformation), 23 showed abnormal disk structure--five showing severe disk destruction and 18 showing less severe abnormalities (inhomogeneous structure, fragmentation, poor delineation, and severe flattening). MR images showed bone abnormalities in 27 of the 36 TMJs, and tomography showed abnormalities in 25 of the 36 TMJs. Good agreement between the two imaging modalities regarding surface irregularities was found. However, MR imaging demonstrated more extensive bone abnormalities than did tomography in 11 TMJs. The potential of MR imaging for depicting bone and soft-tissue abnormalities associated with rheumatic TMJ involvement was clearly demonstrated.