A patient with Darier's disease was treated topically with either 13-cis-retinoic acid 0.1%, all-trans-retinoic acid 0.05% or their cream base only. Both 13-cis-retinoic acid and all-trans-retinoic acid were effective. However, all-trans-retinoic acid had to be discontinued because of irritation. By contrast, 13-cis-retinoic acid was well tolerated and resulted in a complete remission. Both retinoids caused a marked change in the expression of cytokeratins. The most remarkable observation was the expression of cytokeratins 4, 13 and 19 at retinoid-treated areas. These cytokeratins are absent in adult normal or diseased epidermis and hence provide a cell-biological tool to substantiate a retinoid effect.