Increasing data are known for dialogue between neuroendocrine and immune systems recently. Results of molecular genetic studies provided evidences for common languages of these systems by various signals including neurotransmitters, hormones, cytokines. It is proved the immune system is able to produce neurotransmitters and hormones and endocrine organs can even result in cytokines. This new integrative approach allows to investigate the physiologic events and diseases as interactions between the psycho-neuro-endocrine-immune systems. The autoimmune polyendocrine syndromes constitute a heterogeneous group of disorders characterized by loss of immune tolerance to self-antigens. In spite of distinct clinical pictures, molecular genetic studies revealed a common molecular mechanism in the associations of organ-specific diseases. Autoimmune polyendocrine syndrome-1 is characterized by associations at least two out of three cardinal signs: Addison's disease, autoimmune hypoparathyroidism and mucocutaneous candidiasis. This is a rare autosomal recessive syndrome induced by mutations in autoimmune regulator gene. Autoimmune polyendocrine syndrome-2 occurs more frequently and defined as the coexistence of Addison's disease, autoimmune thyroid disease and/or type-1 diabetes mellitus. Autoimmune polyendocrine syndrome-3 is characterized by association of autoimmune thyroid disease and type-1 diabetes mellitus. The HLA and other genes proved to be important in associations of the syndrome-2 and 3 in contrast to autoimmune polyendocrine syndrome-1. Identification of predisposing genetic helps to understand the common mechanisms and provide possibility for early therapy and prevention as well.