Because there are no diagnostic laboratory tests or histopathologic findings, the diagnosis of Behçet's disease (BD) is based on clinical criteria. Various diagnostic criteria have been proposed. In this study, we assessed the sensitivity, specificity and the relative value of the Mason & Barnes, Japanese, Hamza, O'Duffy, Cheng & Zhang, Dilşen and International Study Group (ISG) criteria. Two hundred twenty-eight patients with Behçet's disease diagnosed according to either O'Duffy's or ISG criteria and 89 control patients with a variety of connective tissue diseases, including sarcoidosis, uveitis, erythema nodosum, and granulomatous intestinal disease, were evaluated. ISG and Hamza criteria showed the highest specificity (100%) in discriminating control subjects from the entire cohort. The highest sensitivity value (100%) was found in the Cheng & Zang criteria, which were found to be the most sensitive but the least specific (74.2%). The Hamza criteria had the highest relative value (sensitivity plus specificity) (198.2). Dilşen (196.9) and ISG (196.5) criteria also had high relative values. In this study, Hamza, Dilşen, and ISG criteria performed quite well in diagnosing BD in our country compared to the other criteria sets.