Chronic irradiation of hairless mice with UVB leads to elastosis as evidenced by both histologic means and an increase in skin desmosine content. Treatment with topical all-trans- or 13-cis-retinoic acid causes dose-dependent increments in the area of the dermal “repair zone”; skin desmosine content increases during irradiation but does not change significantly after irradiation is discontinued and retinoic acid treatment commenced. During the course of the irradiation the animals develop permanent wrinkles on the exposed dorsal surface, which can be recorded in plastic impressions. The extent of wrinkling can be quantitated and it has been demonstrated that topically applied retinoic acids lead to the complete effacement of these surface features and that the process appears to be permanent.