Radiation synovectomy is a potential weapon in the therapeutic armamentarium of nuclear medicine. It is an attractive alternative to surgical or chemical synovectomy for the treatment of rheumatoid arthritis. In this article the clinical results obtained with radiation synovectomy from the 1950s through 1992 are summarized and reviewed. Even after taking into account the paucity of well-controlled trials and rigorous clinical follow-up, it is clear that radiation synovectomy is efficacious in controlling the symptoms of rheumatoid arthritis. However, the procedure is not widely used because of concerns about leakage of radioactivity from the treated joint, and the resulting high doses that can be delivered to nontarget organs. New approaches to the preparation of radiolabeled particles for use in radiation synovectomy promise to minimize this leakage and thus allow the full potential of this important radiotherapy to be realized.