Radiologic assessment of the stage and treatment response of rheumatoid arthritis (RA) is based on the presence of bone erosions, joint-space narrowing, and osteoporosis. Most radiologic methods for staging RA lack interobserver correlation and are time consuming. Magnetic resonance (MR) imaging provides excellent depiction of soft-tissue abnormalities of the joints affected by RA, which allows detection of early changes. Nineteen joints of 17 patients with RA were studied with surface-coil MR imaging. Measurable abnormalities demonstrated by MR imaging but not clearly seen on plain radiographs included bone erosions, joint effusion, synovial sheath effusion, and cartilage irregularity and thinning. Seven patients of this group underwent MR imaging before and after 6 months of gold therapy. Four patients had significant interval changes on MR images that were not seen on plain radiographs. MR imaging may become a sensitive and objective method for quantitative assessment of the joint changes of RA.