Extensive evidence now supports the increasing role of all the cross-sectional imaging modalities, but especially MRI and sonography, in investigating rheumatic disease. CT plays a more limited role because of its need for radiation and its relatively poorer soft tissue contrast. MRI provides exquisite detail of all joint and periarticular soft tissues, which can be used to provide earlier and more accurate diagnosis and follow-up of inflammatory arthritides. The application of these techniques should enable better-targeted therapy and evaluation of potential complications.