Background : The course of rheumatoid arthritis (RA) is varied, ranging from mild to aggressive forms, the latter being very difficult to cope with. It has been shown that early diagnosis and treatment reduce joint destruction, preserve function and improve survival. However, prognostic factors capable of guiding the rheumatologist to optimal treatment in the individual patient are largely lacking in clinical practice. Recently, autoantibodies such as anticitrullinated protein antibodies (anti-CCP) can be detected in RA sera and debated as a prognostic factor for RA outcome. Objectives: To identify the relation of anti-cyclic citrullinated peptide antibodies (anti-CCP) with each of RA disease activity, and severity and the role of anti-CCP as a predictor of radiological damage especially in early disease course. Also, to compare their sensitivity and specificity with those of rheumatoid factor (RF) in addressing the radiographic damage.Patients and methods: Sixty RA patients diagnosed by the American College of Rheumatology (ACR) criteria ; their age ranging from 19 to 75 years and disease duration ranging from 3 to 24 months ; were assessed by full history taking, complete clinical examination, routine laboratory investigations, Steinbroker functional classification, modified disease activity score (DAS 28) and Rheumatoid Arthritis Severity Scale (RASS). Study for radiographic damage was done by Sharp's method modified by Van der Heijde. Anti-cyclic citrullinated peptide antibody assay was done for all patients' sera by ELISA. In addition, fifteen normal subjects was tested as control for the cut off value of serum anti-CCP level.Results: Positive anti-CCP antibodies were found in 45% of the studied RA patients and the proportion of positive tests had more swollen joints, more disease activity, more disease severity, higher erythrocyte sedimentation rate (ESR) and higher C-reactive protein (CRP) (P<0.000). The presence of anti-CCP antibodies were associated with significantly higher erosions, joint space narrowing and total damage radiological scores both in hands and feet (P<0.000). Predictor analysis showed that anti-CCP was a significant predictor for joint damage, also low grip strength and high modified disease activity score (DAS 28), while rheumatoid factor (RF) did not. Anti-CCP antibodies had higher sensitivity (85.7%) and specificity (90.6%) for erosions compared with RF (78.6% and 75% respectively). In separate analyses of patients with and without RF, anti-CCP was better than RF for predicting total joint damage and erosion score. Extra-articular manifestations were not associated with anti-CCP.Conclusion: Antibodies to citrullinated protein / peptides determined early in the course of RA by anti-CCP ELISA are good predictors of radiographic joint damage. Patients with anti-CCP antibodies develop a more severe disease course with more radiological destruction compared with RA patients without these auto- antibodies. The use of anti-CCP in clinical practice should make it easier for rheumatologists to reach judicious treatment decisions. Our findings indicate that a simple inexpensive test such as anti-CCP ELISA determination is useful in predicting severe joint destruction during the first two years after onset of RA.