The aim of the study was to test the content serum, erythrocytes and hair copper and the relation between the level of copper and the activity disease in the rheumatoid arthritis (RA) patients. The subjects of this research were 58 persons with RA. In the control group there were 27 healthy subjects. The concentration of copper were determined by atomic absorption spectroscopy. The obtained results showed significant increase of the mean concentration of serum copper in RA patients (19.1 +/- 4.5 micromol/L) in comparison with control group (14.2 +/- 2.7 micromol/L, p < 0.001). The mean level of hair copper was also significantly increased in the examined group (14.3 +/- 4.2 microg/g dry mass) in comparison with healthy subjects (10.4 +/- 3.7 microg/g dry mass, p < 0.01) and considerably lower in erythrocytes (RA patients - 67.6 +/- 13.4 microg/dL, control group--84.2 +/- 8.2 microg/dL, p < 0.001). Moreover, it was established that mean serum copper concentration in the examined group was significantly correlated with erythrocyte sedimentation rate (r = 0.48, p < 0.001) and Ritchie articular index (r = 0.36, p < 0.01) and negatively with hemoglobin (r = -0.41, p < 0.01). Copper content is not dependent on sex, age and disease duration.