Rheumatoid arthritis (RA) is one of the most common autoimmune diseases, affecting 0.5‑1 % of the world population. This systemic disease is characterized by chronic inflammation of the synovial joints and progressive joint degeneration eventually leading to disability of affected individuals. 1 The diagnosis of RA often relies on clinical manifestations and laboratory tests such as rheumatoid factor (RF) and C‑reactive protein (CRP). However, RF is non‑specific for RA and may be present in healthy elderly persons or in patients with other autoimmune and infectious diseases and CRP is a general inflammation marker. Recently, the identification of citrulline as a target of a whole set of autoantibodies like anti‑perinuclear factor (APF), anti‑keratin antibodies (AKA), anti‑filaggrin antibodies (AFA) etc. detected in the sera of RA patients has led to the development of anti‑CCP assays that possess a high specificity for RA. The clinical performance of anti‑CCP assays has been further improved by the use of multiple citrullinated peptides, resulting in a second generation of anti‑CCP assays.