Objectives: To assess the validity of Behçet's Syndrome Overall Damage Index (BODI) and Behçet's Disease Damage Index (BDI) as tools for the detection of damage accrual in Behçet's patients compared to Vasculitis Damage Index (VDI). Also, to evaluate the correlation and the interclass correlation among the 3 indices to find out their consistency. Method: A prospective cohort study was carried out on 102 adult Behçet's disease (BD) patients who were diagnosed according to the International Study Group criteria for BD. Disease severity and organ damage were assessed for each patient by VDI, BDI and BODI at baseline and 1-year follow-up visits. Damage accrual for each index was defined when there was an increase of at least 1 point (Δ ≥ 1) among the baseline and the follow-up visits. Results: Correlations among the 3 indices were significant, with (r = 0.835, P < 0.001) between VDI and BODI, (r = 0.835, P < 0.001) between VDI and BDI, and (r = 0.844, P < 0.001) between BODI and BDI scores. A highly significant positive correlation existed between the 3 indices and age and disease duration. In contrast, the correlation with the BD Current Activity Form was non-significant, which indicates good discriminative validity of the 3 indices. Neuropsychiatric and ocular systems showed a strong interclass correlation among the 3 indices. Regarding detecting damage accrual, BDI was more sensitive than BODI and showed more agreement with VDI. Conclusion: BD damage indices, VDI, BODI and BDI, had good convergent and discriminative validity for the assessment of BD damage. BDI had more sensitivity than BODI to the detection of damage accrual. K E YWORDS Behçet's Damage Index (BDI), Behçet's disease (BD), Behçet's Syndrome Overall Damage Index (BODI), damage accrual