Acitretin, the free acid of etretinate, is less lipophilic and has a much shorter terminal half-life than the parent compound. The present double-blind, randomized study compared the therapeutic effectiveness and the tolerability of acitretin (n = 127) and etretinate (n = 41) in psoriasis. Patients were treated with 40 mg daily for the first 4 weeks and with an individually adjusted dose for the subsequent 8 weeks. The average daily doses of acitretin (0.54 mg/kg/day) and etretinate (0.65 mg/kg/day) were similar. The PASI (Psoriasis Area and Severity Index) scores improved in parallel in the 2 treatment groups. At the completion of the study, the PASI score improvement was 75.8% for acitretin and 70.8% for etretinate. Both acitretin and etretinate resulted in mucocutaneous side effects. Assessments of tolerability by investigators and patients showed a statistically significant difference in favour of etretinate. These results demonstrate that acitretin and etretinate have similar therapeutic effectiveness in psoriasis. Although the tolerance to acitretin was lower than to etretinate, acitretin offers the important advantage of a much shorter period of potential teratogenicity and is, therefore, to be preferred in women of childbearing potential.