We performed radical multiple synovectomy (RaMS) on rheumatoid arthritis (RA) patients who had multiple swollen joints in the mid or late course of RA. The objectives of this operation are to reduce the quantity of RA synovium as much as possible and to increase the efficacy of anti-rheumatic medication in order to achieve remission.2+ Nineteen RA patients who underwent RaMS were followed up for at least 15 months. In this series, anti-rheumatic medications were not changed after the operation, so that the effectiveness of the RaMS could be evaluated. The patients ranged in age from 44 to 73 years (mean: 55.8 years). The male to female ratio was 2:17. Duration after onset of RA ranged from 2 to 29 years (mean: 15.1 years). The swollen joint score according to Lansbury's evaluation of the RA activity index ranged from 7 to 24% (mean: 14.4%). The synovectomized joint score ranged from 7 to 22% (mean : 13.3%). The weight of the excised RA synovium ranged from 19.0 to 109.9 g (mean : 54.0 g). The number of operations was one in three patients, two in 15 patients and three in one patient. The postoperative results indicated that the modified Lansbury's index (morning stiffness, grip power, ESR, joint score), the values of ESR, CRP, Hb, TNF-alpha and IL-6 in the blood, and the peripheral lymphocyte CD4/CD8 ratio were improved, with a statistically significant difference. At 15 months after the operation, ten of the 19 patients (52.5%) satisfied the proposed criteria for clinical remission of RA.(ABSTRACT TRUNCATED AT 250 WORDS)