The most popular research interest in Behçet's Syndrome (BS) is directed to immunological mechanisms. However there are many ways in which BS differs from a classic autoimmune disease. The most important differences lie in the male dominance in severe disease, lack of association with other autoimmune diseases, lack of association with HLA alleles usually seen in autoimmune diseases, lack or paucity of autoantibodies and B cell hyperfunction-especially Sjögren's syndrome- and no definite T cell hypofunction in BS. Perhaps less important points are the peculiar geographic and ethnic distribution, the peculiar clinical features and the lack of response of BS to steroids. The value of immunological data on BS will much increase of we include in each experiment patients with classic autoimmune diseases along with "pure" inflammatory conditions like gout and infectious diseases.