Rheumatoid arthritis (RA) characterized by synovial inflammation and destruction of cartilage and bone. Until now there is no single test that diagnoses RA, however, several blood tests may suggest the presence of this disease. RA is associated with the presence of a number of autoantibodies as such as rheumatoid factor (RF), anti-cyclic citrullinated peptide (ACPA) and antimannose binding lectin (anti-MBL). This study aimed firstly to investigate the presence of anti-MBL autoantibodies in the sera of RA patients and healthy controls and secondly to determine the diagnostic value of this marker in comparison with the classical RF, C-reactive protein (CRP) and ACPA among RA cases. This case-control study was conducted at four health establishments; two public (Al-Thawra Modern General Hospital and National Center of Central Public Health Laboratories) and two private (University of Science and Technology Hospital and Aulqi Specialized Medical Laboratories) in Sana'a city. Ninety-four individuals were enrolled in this study. Forty-seven persons were clinically diagnosed to have RA by a rheumatologist and 47 healthy subjects without RA were used as controls. Sera were separated and tested for presence of serum anti-MBL autoantibodies, ACPA, RF and CRP by a commercially available enzyme linked immunosorbent assay (ELISA) and latex agglutination technique. Study results showed that the meanSD for the levels of serum anti-MBL autoantibodies among RA cases were 394243 ng/ml which were significantly higher than that recorded among healthy controls (217173 ng/ml). The levels of serum anti-MBL autoantibodies were associated with positive RF and CRP tests (p=.02 and .007 respectively), but not with positive ACPA test (p=.42). The result of this study showed higher levels of serum anti-MBL autoantibodies among RA cases comparing with the healthy controls and reveal an association with positive results for RF and CRP, but not with ACPA. Therefore, the anti-MBL antibody levels may associated with systemic autoimmune diseases and might not exclusive to RA.