This 14-week study will observe the gene expression of certain immune cells in patients with rheumatoid arthritis who receive etanercept, infliximab, and adalimumab. Patients at the National Institute of Rheumatology and Physiotherapy, Budapest, who are already scheduled to receive an anti-TNF agent will be asked to participate in this study. Patients will receive their treatment (etanercept, infliximab, or adalimumab) as scheduled, and have blood samples collected during the study and analyzed by the laboratory. Patient's response to their treatment will also be studied based on x-rays and other examinations.

Only patients who - regardless of this study - are scheduled and permitted to receive anti-TNF-alpha treatment because of their RA will be asked to participate. No patient will be recruited only for the sake of the study. The prescribing physicians will not be influenced by the study as to what form of anti-TNF-alpha therapy they should select.

Inclusion Criteria:

• Must have active RA (DAS28 >5.1)
• Must have x-ray evidence of an erosive disease,
• Must be eligible for but have never received any anti-TNF treatment,
• Must fulfill the 1987 criteria of the American College of Rheumatology classification criteria for a diagnosis of RA, for at least 3 months,
• Must have failed standard therapy (methotrexate or leflunomide).

Exclusion Criteria:

• Must not be a women who is pregnant or breastfeeding,
• Must not have a history of any malignancy,
• Must not have an active infection,
• Must not be prone to infection,
• Must not have tuberculosis, hepatitis B, hepatitis C, or HIV,
• Must not have septic arthritis of a native prosthetic joint within the last 12 months,
• Must not have NYHA grade 3 or 4 heart failure,
• Must not have a history of demyelinating disease or systemic lupus erythematosis.

Subjects will be recruited from a single center at the National Institute of Rheumatology and Physiotherapy, Budapest, the largest center for biological therapy in Hungary. Subjects will be patients who are scheduled and permitted to receive anti-TNF-alpha treatment due to their rheumatoid arthritis.