Behçet's disease is an inflammatory disorder affecting many organs including the eye and one of the most common sight-threatening causes in countries around the Mediterranean basin and in the Asia including Japan, Korea and China. A number of clinical and laboratory findings suggest the significant involvement of the immune alterations in the pathophysiology and the pathogenic mechanisms of Behçet's disease. The immune alterations demonstrated in the disease include the alteration of the T cell circuitry and abnormal functions of the leukocyte. Because immunologic processes are believed to be in the chain of events in the manifestation of Behçet's disease, various agents capable of modulating the immune responses have been used to treat the disease. These drugs include corticosteroids, colchicine, cytotoxic agents, and immunophilin ligands (cyclosporine and FK506). This paper reviews the experimental and clinical investigations to analyze the immunopharmacological activities of these immunosuppressive agents in animal models and in patients with Behçet's disease.