Regulatory T cells (Tregs) play a vital role in maintaining homeostatic balance within the immune system. Tregs are required for mediating normal immune responses against pathogens and then terminating such responses when no longer required. However, Tregs also provide important regulation of autoimmune responses, specifically in preventing autoimmunity. They are defined by expression of surface markers and production of specific cytokines that dictate their mode of action. In this review we discuss the recent advances in the understanding of the biology of Tregs, with a focus on their role(s) in human endocrine disease. In addition, recent discoveries of how hormones influence the development and function of Tregs are highlighted.