Autoimmune endocrine diseases are serious disorders that utilize immense health care resources and cause tremendous disability. They include type 1 diabetes mellitus, thyroiditis, Graves disease, Addison disease, and polyglandular syndromes. Analysis of the basis of autoimmune diseases has been aided by the application of new knowledge in immunologic physiology. Recent investigations using these techniques have revealed complicated disorders that have varied pathogenesis and complex genetic predispositions. While the mainstay of treatment for these diverse diseases remains the replacement of hormones produced by the damaged endocrine organ, investigations into the pathogenesis of these disorders provide hope for the development of specific therapeutic measures to block their pathologic basis.