Molecular and cellular mechanisms of glucocorticoids (GCs) action and the effects of GCs have been briefly reviewed. GCs exert their effect by binding to GC receptor, which are direct modulators of gene transcription. GC receptor is a member of steroid receptor superfamily and consists of several functional domains including DNA binding and hormone binding. GC receptor was first shown to be a potent activator of transcription, but recently, GC receptor has also been shown to repress expression of various of genes through interaction with other transcriptional factors. GC has a variety of physiological and pharmacological effects on carbohydrate and lipid metabolism, immunological functions and inflammatory processes, fluid and electrolyte homeostasis, bone and mineral metabolism, musculoskeletal tissues and so on. The details of these effects have been described.