The mode of action of benzoyl peroxide in acne is three-fold, i.e. sebostatic, comedolytic and inhibitory to P. acnes in-vivo. Benzoyl peroxide is the topical treatment of choice in acne vulgaris. This agent is well tolerated by most patients. Primary irritant dermatitis can be avoided by less frequent application and the true incidence of contact sensitivity is low. The gel preparation has achieved a high degree of cosmetic acceptability. A synergistic effect with retinoic acid can be demonstrated. Tolerance to benzoyl peroxide develops in most subjects necessitating more vigorous therapy, usually after two or three weeks of treatment. Many acne sufferers with mild or moderate disease can avoid long-term oral antibiotic treatment by the judicious use of benzoyl peroxide topically.