Total plasma zinc levels in patients with rheumatoid arthritis on different therapeutic treatments were determined in conjunction with total serum proteins, serum albumin and globulin, and articular index of joint tenderness, erythrocyte sedimentation rate, rheumatoid factor, serum copper, and serum iron. There were significantly lower zinc levels in patients with rheumatoid arthritis on nonsteroidal anti-inflammatory drugs than in patients on levamisole and penicillamine. Zinc levels correlated positively with serum albumin, and there was an inverse correlation between zinc levels and both ESR and globulin concentration in all rheumatoid patients. However, the correlation coefficient varied in the different treatment groups. The results of this study support the hypothesis that low plasma zinc level in rheumatoid arthritis is one of the nonspecific features of inflammation.