The concentration of selenium in serum (S-Se) was studied in 20 patients and glutathione in erythrocytes (E-GSH) in 16 patients with rheumatoid arthritis (RA) at onset and after 3 and 6 months of antirheumatic therapy with aurothiomalate (19 cases) or with D-penicillamine (one case). The values were compared to those of age and sex matched healthy controls. S-Se was significantly (p less than 0.01) lower in RA patients at the onset of the trial, but increased to the level of the controls during the follow-up. On the other hand, there was no difference in E-GSH between the patients and their controls before the onset of antirheumatic medication but the increase in E-GSH of RA patients during the trial was highly significant (p less than 0.001). Nevertheless, neither S-Se nor E-GSH correlated to changes in clinical or laboratory indicators of disease activity or to the development of new erosions in X-ray. It is concluded that changes in rheumatoid activity or disease progress occur independently of changes in S-Se or E-GSH.