Magnetic resonance imaging (MRI) was performed in 71 wrists of 39 rheumatoid arthritis patients. There were 2 males (3 wrists) and 37 females (68 wrists) with an average age of 55.4 years. Synovial proliferation and bone erosion appeared as low intensity areas on T1-weighted MRIs and as high intensity areas on T2-weighted images. Discrimination of synovial proliferation was improved by Gd-DTPA enhancement. These lesions could be detected in early rheumatoid arthritis patients whose plain X-ray images lacked abnormal findings. We found MRI to be a useful method for detecting bone and soft tissue lesions of RA, especially of early RA patients. MRI is also useful in evaluation of drug therapy and pre-operative planning.