The present review provides an update of the available data and discusses research issues of ultrasound (US) imaging in rheumatoid arthritis (RA). Currently the principal indications for using US in the assessment of patients with RA include: detection of sub-clinical synovitis, demonstration of bone erosion undetected by conventional radiography, detailed assessment of tendon pathology and guided injection and aspiration of joints and soft tissues. Future potential applications are likely to include short and long term therapy monitoring and early detection of cartilaginous changes in RA. The main priorities requiring the attention of investigators include: addressing validity issues, especially those related to criterion and discriminator validity, development of international consensus on scoring systems, evaluation of the role of power Doppler in the assessment of disease activity, development of a specific training programme for rheumatologists performing US and investigation of the potential of 3D US using a volumetric probe.