disease duration; 10.25±4.61 years), and 19 healthy subjects (mean age; 40.26±5.11 years) served as controls. Anti-CCP antibodies and Anti-MCV antibodies were measured using ELISA. Results: In all RA patients, mean antiCCP level was 69.07±90.43 U/ml and anti-MCV level was 665.77±1040.19 U/ml. In patients with AS, the mean anti-CCP level was 10.7±5.22 U/ml and anti-MCV level was 40.54±20.15 U/ml. In healthy controls, the mean anti-CCP level was 11.11±7.65 U/ml, anti-MCV level was 23.12±12.04 U/ml. In patients with active RA, the mean serum anti-CCP level was 100.54±98.07 U/ml and anti-MCV level was 998.74±1154.93 U/ml. In patients with inactive RA, the mean serum anti-CCP level was 8.77±1.55 U/ml and anti-MCV level was 27.59±23.10 U/ml. According to these results; In patients with RA, the mean serum anti-MCV and anti-CCP levels were significantly high compared to patients with AS and healthy controls (p=0.002, p=0.001, p=0.002, p=0.001 respectively). The mean serum anti-MCV and antiCCP levels were significantly higher in active patients with RA than in inactive patients with RA patients (p=0.001 and p=0.001 respectively). In inactive patients with RA, the mean serum anti-MCV and anti-CCP levels were similar in patients with AS and healthy controls patients (p=0.484, p=0.308, p=0.09 and p=0.222 respectively). The mean serum anti-MCV levels were correlated with DAS 28 (r=0.531, p=0.001), VAS score (r=0.332, p=0.01), ESR (r=0.458, p=0.001), serum CRP levels (r=0.568, p=0.01), serum RF levels (r=0.529, p=0.001), swollen joints number (r=0.525, p=0.001) and tender joints number (r=0.638, p=0.001). Conclusion: As a result; measurement of serum anti-MCV levels is useful for diagnosis of RA and combined use of anti-MCV and RF may be more useful prognostic factor than either method alone, RF and anti-CCP.