Abstract : Anti-carbamylated protein (anti-CarP) antibodies have been detected in patients with Rheumatoid arthritis (RA) and has been postulated to be associated with more severe joint involvement and disease activity. We aim to investigate diagnostic value of anti-CarP antibody in Indian RA patients. Cross-sectional study included 150 RA patients diagnosed by 2010 ACR-EULAR criteria. Demographic and clinical data, disease activity scores, X-ray images, medication history was recorded. Laboratory tests included C-reactive protein, rheumatoid factor, anti-citrullinated protein antibodies, and anti-CarP antibody. Receiver-operating characteristic curve study demonstrated significant area under the curve, 0.814, confidence interval of 0.746 - 0.882, sensitivity 85.26%, specificity 92.73%, positive predictive value 95.29 and negative predictive value 78.46. Cut off value of anti-CarP Ab was ≥ 13.48 U/Ml. Among 150 RA patients, anti-CarP Ab was positive in 71, RF positive in 108 patients; by joining anti-CarP antibody with RF there was 15.3% increase in seropositivity. 39.4% of ACCP negative RA had positive Anti-CarP Ab. Population with RF negative and ACCP negative, anti-CarP was found in 48% cases. Among 71 patients with anti-CarP Ab positivity, 54.9% exhibited joint deformities, 32.4% extra articular manifestations, 38% joint erosions in X-ray. 69.4% with high disease activity (DAS28 ≥ 3.2) had anti-CarP Ab positivity. ACCP demonstrated no statistically significant association with joint involvement. Anti-CarP antibody is a useful biomarker for detection of sero-positivity in ACCP negative subgroup of Rheumatoid arthritis patients for early initiation of DMARDs therapy and as a prognostic indicator for a more severe disease course.