Retinoids are analogs of vitamin A that exert multiple effects on cellular differentiation and proliferation, the immune system, and embryonic development. A thorough understanding of their mechanisms of action, formulations, administration, and potential adverse effects enables dermatologists to effectively and safely treat patients with a variety of cutaneous disorders. Topical retinoids are used to treat a number of conditions including acne, photoaging, and psoriasis, with skin irritation representing a limiting factor. Oral retinoids are the most effective drugs available for severe acne (isotretinoin) and many disorders of cornification (acitretin and isotretinoin), and they are also helpful in the management of inflammatory and neoplastic skin diseases; careful patient selection and monitoring are required due to their teratogenicity and other potential toxicities