Auto-immunity may occur in all endocrine tissues, with a particular prevalence in thyroid and pancreatic islets. The most demonstrative clinical expressions of this auto-immunity are Graves’ disease and insulin dependent diabetes. In the former, extensive data are available upon the immunological disorders seen in peripheral blood as well as in the thyroid itself. The predisposal profile of such diseases is quite well delineated (genetic markers in HLA system, organ-specific T suppressive deficiency). On the other hand, the mechanisms implicated in the onset of auto-immunity are still questioned, the classical viral infection being scarcely demonstrated. Clinical observation registers frequent stressful life events just before the onset of these diseases, but there are few convincing data in the literature. The recent findings on the close relations between the immune system and the central nervous system lead to conceive an actual psychoneuro-endocrine-immune axis. This axis might explain the eventual priming effect of stress in patients predisposed for an organ-specific auto-immunity.