The aim of the study was to explore whether the serum level of interleukin 6 (IL-6) is correlated with matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs), and with clinical markers of the disease activity in rheumatoid arthritis (RA). Concentrations of IL-6, interstitial collagenase (MMP-1), stromelysin-1 (MMP-3), gelatinase B (MMP-9), TIMP-1 and TIMP-2 were measured with an ELISA technique in serum of 32 RA patients. We found the correlations between IL-6 and total measured MMPs (p<0.001), and total measured TIMPs (p<0.001). Furthermore, serum IL-6, MMPs and TIMPs correlated with the erythrocyte sedimentation rate, C reactive protein level, the number of tender and swollen joints, and Ritchie articular index (RAI). We conclude that analysis of the serum IL-6, MMPs and TIMPs levels may be useful in the assessment of the RA activity.