Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by chronic synovitis and bone damages, which consist of joint destruction. Clinical trials have shown that anti-tumour necrosis factor (TNF) drugs are effective in patients with rheumatoid arthritis (RA) refractory to disease-modifying antirheumatic drugs (DMARDs). At about the same time as the European approval of the third anti-TNF agent for treating rheumatoid arthritis (RA) patients, the Italian Society of Rheumatology (Società Italiana di Reumatologia [SIR]) started a database for the registration and active follow-up of patients with RA treated with biological response modifiers. Since 1999, all patients with RA (ACR criteria) and treated with at least one dose of an anti-TNF agent at four Rheumatology Centres in Lombardy (northwest Italy) have been included in the Lombardy Rheumatology Network (LORHEN) registry in order to track the efficacy and safety of the three available TNF inhibitors during the first three years of treatment.