At present, four main types of autoimmune polyglandular syndromes (APS) are distinguished. Type 1 APS is associated with candidiasis, primary hypoparathyroidism, and primary adrenal insufficiency developing in the childhood as a result of mutations in the AIRE gene. Type 2 APS involves primary adrenal insufficiency in combination with autoimmune thyroid diseases and/or type 1 diabetes mellitus. Type 3 APS is characterized by the combination of autoimmune thyroid diseases with other endocrine and non-endocrine autoimmune pathologies in the absence of adrenal cortical dysfunction and hypoparathyriodism. Type 4 APS is presented by the combinations of autoimmune diseases other than the aforementioned ones. The above syndromes usually manifest themselves at the age between 20 and 60 years; they are of the polygenic type and associated with the genetic markers, such as HLAII-complex haplotypes, CTLA-4, PTPN22, FOXP3 genes, etc. In addition, the latent forms of APS have been described that occur in the populations much more frequently than the manifest disorders. These latent diseases can exert strong influence on the compensation and risk of complications of the underlying pathology. Of great importance in this context is the timely identification of the groups of patients at risk of developing clinical forms of APS among the subjects presenting with a single endocrine pathology.