We investigated the clinical efficacy of topically applied calcipotriol in six patients with congenital ichthyosis, using a double-blind, bilaterally paired, comparative approach. Unilateral improvement, in favour of the calcipotriol-treated side, was observed in three patients with lamellar ichthyosis. A beneficial response was also observed in a patient with bullous ichthyotic erythroderma of Brocq. No clinical side-effects or laboratory anomalies were observed. This study indicates that calcipotriol constitutes a new and promising approach in alleviating disorders of keratinization characterized by hyperproliferation, other than psoriasis.