Hormones are specific regulatory molecules that have potent effects on the major determinants of the development and the integrity of the skeleton and oral cavity including periodontal tissues. It is clear that periodontal manifestations occur when an imbalance of these steroid hormones take place. The authors conducted a Medline search up to 2004 and in addition, a manual search was also performed including bibliographies of relevant papers, review articles and books. This review focuses on the effects of endogenous sex hormones on the periodontium and the goal was to inform and update practitioners' knowledge about the impact of these hormones on periodontal status. In addition, this review article will analyze how these hormones influence the periodontium at different life stages such as puberty, menstruation, pregnancy, menopause and post-menopause. Moreover, the effects of contraceptives and hormone replacement therapies on the periodontium will be discussed. It is clear that endogenous sex steroid hormones play significant roles in modulating the periodontal tissue responses. A better understanding of the periodontal changes to varying hormonal levels throughout life can help the dental practitioner in diagnosis and treatment.