Background: Numerous serological markers of RA have been describedover the past 50 years. Among all these, Anti Citrullinated Protein/PeptideAntibodies (ACPA) have been proven to be specific, diagnostic andprognostic markers in RA. The newest member of this autoantibody familyis Anti- Mutated Citrullinated Vimentin (MCV).Aim of work: The aim of this work was to evaluate the prevalence of Anti-Mutated Citrullinated Vimentin Antibodies (MCV) in rheumatoid arthritispatients and to correlate it with disease activity, various diseasemanifestations and prognosis.Patients and methods: 50 RA patients (94% females and 6% males)fulfilling the 1987 ACR revised classification criteria for RA having meandisease duration of 8.33±7.22 years and 30 healthy controls (40% femalesand 60 % males) were included. All RA patients were subjected to: Clinicalassessment of disease activity by taking full history, general and localexamination, measurement of 28 joint count of tender and swollen jointswith calculation of disease activity score (DAS-28) for each patient togetherwith assessing functional ability with Modified Health AssessmentQuestionnaire (MHAQ). Complete blood count, erythrocyte sedimentationrate and rheumatoid factor were performed. Anti-MCV and anti-CCP assayswere performed by ELISA in patients and controls. RA patients were thenclassified into; anti-MCV positive and anti-MCV negative groups forstatistical comparison. Plain X-ray was performed on the hands and wristsand scored by Sharp score. Results: A highly significant elevation of serum anti-MCV in RA patientswas detected when compared to controls. Anti-MCV was detected in 42patients (84%) and in 6 healthy controls (20%) giving a specificity of 84%and a sensitivity of 80%. There was no significant difference between anti-MCV positive and anti-MCV negative patients as regard parameters ofdisease activity represented in ESR and DAS 28, however, there was asignificant difference between anti-MCV positive and anti-MCV negativepatients as regards MHAQ and Sharp scores. In addition, there were nosignificant differences between RA patients who were anti-MCV negativeand those who were anti-MCV-positive with respect to age, sex, diseaseduration. On the other hand, there was a highly significant elevation ofserum anti-CCP in RA patients when compared to controls, as anti-CCP wasdetected in 35 patients (70%) and in none of the healthy controls giving asensitivity of 70% and a specificity of 100%. However, there was nosignificant correlation with either anti-MCV or anti-CCP as regards toneither the qualitative nor the quantitative data except for RF which wassignificantly more frequent with anti-CCP than anti-MCV.Conclusion: Anti-MCV antibodies bore a sensitivity of 84 % and aspecificity of 80% while anti-CCP bore a sensitivity of 70 % and asignificantly higher specificity of 100 %. And according to these findings,the anti-MCV assay did not provide significant additional diagnostic valueover the already established anti-CCP assay nor did it correlate with diseaseactivity. For now, it seems that the only obvious advantage of positive anti-MCV test is a significantly closer association with radiologic progression,thus making the anti-MCV a good predictor of more aggressive and erosive disease.