Tumour necrosis factor alpha (TNF-alpha) and matrix metalloproteinases (MMPs) play an important role in the pathogenesis of rheumatoid arthritis (RA). The present study was conducted to investigate whether the serum level of TNF-alpha is correlated with MMPs and tissue inhibitors of metalloproteinases (TIMPs) in RA patients. Serum concentrations of TNF-alpha, interstitial collagenase (MMP-1), stromelysin-1 (MMP-3), gelatinase B (MMP-9), TIMP-1 and TIMP-2 were measured by ELISA in 34 patients with RA. We found the TNF-alpha to correlate with MMP-1, MMP-3, MMP-9 and total measured MMPs serum concentrations (p < 0.05 for all comparisons). Furthermore, serum TNF-alpha, MMP-1 MMP-3, MMP-9 and TIMP-1 levels correlated with markers of disease activity such as the erythrocyte sedimentation rate, C reactive protein level and the number of swollen joints. No associations were observed between TNF-alpha and TIMPs serum concentrations. Our results support the concept of the regulation of the MMPs synthesis by cytokines such as TNF-alpha. We conclude that the measurement of the serum TNF-alpha, MMPs and TIMP-1 concentrations may be useful in the assessment of RA activity.