Abstract: Alarmins are a bunch of recently discovered endogenous substances which can enhance the immune function of organisms.These substances exist in various cells,helping the body to fight against external stimuli.There is an abnormal expression of alarmins,e.g,,defensins,cathelicidin,eosinophil-derived neurotoxin,some high-mobility group proteins,in many skin diseases.The expression and function profiles of alarmins vary in different skin diseases.They may suppress inflammation,break immune balance,induce malignant transformation of ceils,promot stromal hyperplasia and fibrosis,etc.The changes of alarmins may either be involved in the pathogenesis of diseases,or be just secondary reactions.There have been alarmintargeted drugs,which are expected to benefit the recovery of patients.