Retinoids play a vital role in the treatment of acne because they act on the primary lesion, the microcomedo. They are synthetic derivatives of vitamin A (retinol), and are selected for their effectiveness. Several compounds are used for acne, either in topical or systemic form.We describe and compare the different topical retinoids, tretinoin (all-trans-retinoic acid), isotretinoin (13-cis-retinoic acid), adapalene (derived from naphthoic acid), and tazarotene (acetylenic retinoid). They act mainly as comedolytics, but anti-inflammatory actions have also been discovered recently. The retinoids have great beneficial effects, but also some adverse effects, the main one being teratogenicity. It is preferable not to use them in topical form for pregnant women, although a pregnancy test is only compulsory for tazarotene. Only isotretinoin is used in systemic form. It acts on all the factors of acne and offers long remissions, and sometimes complete cures. Precautions must be taken for women of childbearing age due to its teratogenicity. It is also important to be aware of its other adverse effects, explain them to the patient and, if possible, deal with them in advance.