Acitretin (Ro 10-1670, etretin) is the free acid derivative of etretinate. This compound possesses a much shorter half-life of elimination than etretinate and was therefore proposed for clinical development. A total of 635 patients with various dermatoses were studied in 12 main clinical trials performed in Europe and in the United States. It was shown that acitretin is effective in the treatment of psoriasis and other diseases of keratinization. Doses between 25 and 35 mg per day are recommended to initiate treatment since marked improvement or clearing was obtained in the majority of patients within this range. Hypervitaminosis A signs and symptoms have been observed in patients treated with acitretin. It is concluded that the efficacy and safety profile of acitretin resembles that of etretinate.