Abstract： Sarcoidosis is a kind of systematic granulomatous disease of complex etiology without caseous necrosis.It often involves multiple organs such as the lung and skin.Glucocorticoids are usually effective for the control of sarcoidosis.It is considered that sarcoidosis is an abnormal immune response to one or multiple unknown antigenic stimuli in individuals with genetic predisposition.The real etiology of sarcoidosis has not been clarified,and appears to be associated with infection,heredity,occupation,environment,and so on.There seems to be a close relationship between sarcoidosis and infections with Mycobacterium,Propionibacterium,virus,richettsia,fungi,etc.