The treatment of acne is based upon simple pathogenic arguments, but needs to be adapted to the type of acne. Patients must always be informed that it is long and difficult and that no significant response will be expected before 2 to 3 months of regular treatment. The authors present the different therapeutic agents and strategies. Isotretinoin should be used only in severe acne after failure of at least 3 months of a well conducted classical treatment and in nodulo-cystic acne; because of its major side effect of teratogenicity its use in adolescent girl's requires pregnancy testings before and during treatment and an effective contraception.