Background. Antibodies against cyclic citrullinated peptide (anti-CCP) are considered to be specific for rheuma-toid arthritis (RA). Objective. To assess the clinical significance of anti-CCP antibodies in a co-hort of patients with juvenile idiopathic arthritis (JIA) and if they can be used to identify patients with an unfavourable course of disease. Methods. 68 serum samples were investigated. 45 patients were diagnosed with JIA (15 male and 30 female) aged 1.9-17.3 years (median 12.9 mean

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... 0). 5 patients had pol-yarticular (RF negative), 2 polyarticu-lar (RF positive), 25 oligoarticular JIA, 6 enthesitis related arthritis, 2 psoriatric arthritis, 3 patients had sys-temic disease and 2 unclassified arthritis. 23 samples were taken from patients with non-inflammatory cardiac diseases undergoing interventional cardiac therapy. Enzyme-linked immuno-sorbent assay (ELISA; Euroimmun, Lübeck, Germany) was used for the detection and quantification of anti-CCP antibodies in patients with JIA. Results. Overall, anti-CCP antibodies were found in 2.9% (2/68) of all samples and in 4.4 % (2/45) patients with JIA. Conclusion Anti-CCP antibodies are associated with RF positive polyarticu-lar course of JIA. Anti-CCP antibodies are not relevant for other subgroups of JIA. Therefore anti-CCP Abs in patients with JIA should not be investigated routinely.