Background: Behçet’s disease (BD) activity assessment is a major concern since a treat-to-target approach may lead to a better prognosis. The first patient-reported assessment instrument, the Behçet's Syndrome Activity Score (BSAS), is useful for routine clinical use. Aim: To evaluate the validity and the reliability of the translated Arabic version of BSAS (Ar-BSAS) in assessment of BD activity, and discriminate its cut-off point for disease acitivity. Patients and methods: Seventy BD patients were included in the study. The BSAS score was translated into Arabic language. The reliability and the validity were evaluated. Results: The Ar-BSAS each item and the total score demonstrated a high internal consistency and Cronbach’s alpha coefficient (0.881, to 0.997). A significant positive correlation between the total score of the BSAS with the BDCAF (r=0.891, p<0.001**), the BSAS with the MHAQ (r=0.813, p<0.001**) and between the total score of BSAS and ESR, CRP indicating high convergent validity. The BSAS cutoff value for disease activity was (15.5) in comparison with the BDCAFwith high area under the curve 0.972 at 95% confidence interval (CI) on the receiver operating characteristic curve (ROC). Conclusion: The Arabic version of the BSAS (Ar- BSAS) is a reliable, valid and accurate patient reported measure for disease activity that could be used to evaluate disease activity and enhance the therapeutic management choices in routine clinical practice.