ABSTRACT: Rheumatoid arthritis (RA) is a systemic autoimmune disease of unknown etiology that is characterized by chronic joint inflammation which often leads to joint destruction. RA affects 0.1–1.1% of the general population worldwide. RA has a significant negative impact on the ability to perform daily activities, including work and household tasks, and health-related quality of life, and it increases mortality. Autoantibodies in RA patients provide many clues to the underlying disease pathophysiology, and their formation is associated with environmental risk factors such as smoking. The presence of anti-citrullinated protein antibodies (ACPA) in rheumatoid arthritis (RA) indicates a breach in immune tolerance. Recent studies indicate that this breach extends to homocitrullination of lysines with the formation of anti-carbamylated protein (anti-CarP) antibodies. Anti-carbamylated Protein (anti-carP) antibodies are antibodies that target carbamylated proteins, (anti-CarP antibodies) have been described as a biomarker in rheumatoid arthritis (RA). Carbamylation is a posttranslational modification resulting from the conversion of lysines into homocitrullines that requires the presence of cyanate. anti-CarP antibodies might represent a promising marker to predict joint damage and disease activity in RA patients. Anti-cyclic citrullinated peptide (anti-CCP), recent studies have indicated that anti-CCP is sensitive and specific diagnostic and prognostic markers for RA. In particular, anti-CCP appears to be more specific than RF in the diagnosis of RA and may also be better predictors of erosive disease. Accumulating evidence has confirmed that anti-CCP is very useful in the diagnosis of RA.