As one category of the most essential steroid hormones, glucocorticoids have been acknowledged for long, and their therapeutic benefits have been broadly used in clinical treatment, particularly in anti-inflammation cases. Glucocorticoids controls several processes in the body also with the mobilization of energy stores, immune system, gene expression, and upholding of the homeostasis as well as the stress response, this is not unexpected that the theory of "glucocorticoids" is talked about in almost all medical books that aims on definite organs or systems such as the cardiovascular system, the immune system, and the neuroendocrine system. This book aims to reveal the newest researches linked to glucocorticoids, also examines prenatal glucocorticoids affecting the placental development and its consequences on adulthood and the clinical use of glucocorticoids in the treatment of various diseases.