Objective Patients with ulcerative colitis (UC) and Crohn's disease (CD) were not represented in the diseased controls group that had been utilised in the development of the International Study Group (ISG) criteria for the diagnosis of Behcet's syndrome (BS). Having similar features, both of these conditions can pose problems in the differential diagnosis of BS. Moreover there has been a recent awareness of coexistence of BS and familial Mediterranean fever (FMF). The aim of this study was to reassess the performance of ISG criteria among patients with BS and other rheumatological conditions, specifically including those with CD, UC, and FM
