Due to similar manifestations of intestinal Behcet`s disease (BD) to those of other colitis such as Crohn`s disease or intestinal tuberculosis, it is still challenging for gastroenterologist to accurately diagnose intestinal BD in patients with ileo-colonic ulcers. Moreover, no reliable diagnostic criteria for intestinal BD have been developed yet. Therefore, IBD Study Group of KASID was formulated to establish the guideline for the diagnosis of intestinal BD using a modified Delphi process. The novel diagnostic criteria for intestinal BD were developed based on two aspects; colonoscopic findings and extra-intestinal systemic manifestations, in which patients were categorized into 4 groups including definite, probable, suspected, and non-diagnostic for intestinal BD. Furthermore, Disease Activity Index for intestinal BD was developed through a Korean multicenter study. These diagnostic and disease activity guidelines will contribute to understand intestinal BD