Abstract: Comedones have been observed by SEM in 27 cases of acne vulgaris.It mainly consists of more cohesive keratinized cells,sebum,bacteria and spores.There are only loose keratinized cells without bacteria and spores in comedones in two cases of grouped perk iorbital comedones and a case of nevus comedonicus,The authors concluded that accumulated sebum,Corynebacterium acnes and Pityrosporum ovate map plan an important role in the pathogenesis of acne vulgaris.