Acne vulgaris is a self-limited disease, seen primarily in adolescents. Most cases of acne are pleomorphic, presenting various lesions consisting of comedones, pustules, and nodules. Although it has been traditionally classified as a disease of the sebaceous gland, it actually involves the pilosebaceous unit. There are four major principles in the treatment of acne: ① correct the altered pattern of follicular keratinization; ② decrease the sebaceous gland activity; ③ decrease the follicular bacterial population; and ④ produce anti-inflammatory effect. The natural course of acne varies greatly, and therefore, the determination of the therapeutic efficacy of medications for the treatment of acne is far from being simple.