The aim of this study was to determine the activation level of the pro-inflammatory transcription factor nuclear factor kappaB (NF-kappaB) in lymphocytes of patients with rheumatoid arthritis (RA) before and during an anti-tumor necrosis factor alpha (TNFalpha) therapy (adalimumab). In addition, we analyzed the inflammatory markers, interleukin 6 (IL-6), and C-reactive protein (CRP) and investigated the expression of rheumatoid factor (RF) and anti-cyclic citrullinated peptide (anti-CCP) autoantibodies in patients' sera. Twenty RA patients and 20 control subjects were investigated. RA patients' characteristics were evaluated by radiography and disease activity score 28 (DAS 28). Twelve weeks of adalimumab therapy was effective in the treatment of RA patients, as shown by a significant improvement of the DAS 28. The inflammatory markers IL-6 and CRP were significantly different in sera of RA patients compared to the control group before the onset of therapy and exhibited a tendency to return to normal levels during the first 12 weeks of therapy. We measured a comparable activation level of NF-kappaB in lymphocytes of control subjects and of RA patients before starting adalimumab therapy. During the following 12 weeks, no significant changes in the activation levels of both NF-kappaB subunits were detected. Serum concentration of RF was significantly lower after 12 weeks, whereas anti-CCP antibody level remained constant.