Department of Clinical Immunology was newly established in April 2021 to treat a wide variety of autoimmune diseases. Prof. Motomu Hashimoto was appointed as the first professor in the department. We treat autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematosus, polymyositis/dermatomyositis, systemic sclerosis, vasculitis syndrome, mixed connective tissue disease, Behcet’s disease, adult-onset Still’s disease, IgG4-related disease, and so on. Our department aims to maximize the therapeutic effect by actively treating patients with glucocorticoids, immunosuppressive agents, immunomodulatory drugs, and molecularly targeted agents, and by selecting appropriate drugs for each patient’s condition.