Objective. Behcet's disease (BD) is a variable vessel vasculitis. The most widely used classification criteria for adults is the International Behcet's Study Group (ISG) criteria. Recently, the paediatric BD (PEDBD) classification criteria has been developed for children. For disease activity, there are mainly two severity scores; the Iranian BD dynamic activity measure (IBD-DAM) and BD current activity form (BDCAF). We tested the performances of PEDBD and ISG criteria and the correlation between severity scores and physician global assessment (PGA) in children with BD.