The mainstays of topical acne therapies have consisted of topical tretinoin (retinoic acid) and topical antimicrobial agents including benzoyl peroxide, the antibiotics clindamycin and erythromycin, and more recently combinations of these drugs.More recently, the availability of screening assays for retinoids utilizing nuclear receptors has led to two new non-vitamin A retinoids; viz., adapalene and tazarotene. In addition, new formulations of tretinoin in microsponges and complexed to polymers, both of which decrease the irritation potential, have been introduced. In addition, topical azelaeic acid has recently been introduced to the U.S. These new agents have certain advantages and situations in which they are preferable to older agents.Clinical efficacy data, however, do not indicate that they are more efficacious.