Anti-cyclic citrullinated peptide antibodies were recently shownto be highly specific for seropositive RA (98%), with a sensitivity of 68%utilizing a simple ELISA assay. Furthermore, 35% of seronegative RApatients were anti-CCP positive. In addition, a recent study demonstratedanti-CCP antibodies in 70% of patients in the early stages of RA. Becauseof its high specificity, the anti-CCP test should be extremely valuable inthe diagnosis of RA, in the differential diagnosis of RF-positive disorderspotentially confused with RA, in confirming a diagnosis of RA inseronegative polyarthritis and in the diagnosis of RA in early synovitispatients.