There are several therapeutic alternatives in the local treatment of rheumatoid arthritis (RA): intraarticular corticosteroids, chemical synoviorthesis, surgical synovectomy and synoviorthesis with radioisotopes. We present the results of an observational study on radioisotopic synoviorthesis carried out in the Valencian health care area from January 1989 to May 1997 which included 108 synoviortheses performed in 51 patients. This study aimed to assess the efficacy and safety of radiosynoviorthesis in the treatment of RA which had not responded to conventional treatment. Good and moderate results were obtained in 76.2% of the cases, there being significant differences in the efficacy of synoviorthesis in patients with and without advanced radiographic alterations. There were few side effects (3.7%). We conclude that radiosynoviortesis is a useful and safe therapeutic tool in RA that does not respond to conventional treatment, that it is more effective in large joints with little cartilaginous deterioration and that its repeated use does not decrease the expected therapeutic effect.