We performed a 22-month trial of topical tretinoin (retinoic acid) in the treatment of photoaging. Thirty patients participated in a 4-month, randomized, blinded, vehicle-controlled study that has been reported previously; 21 patients continued tretinoin therapy on an open-label basis, participating in the study for a total of 10 months, and 16 patients continued for 22 months. During the open-label study, the statistically significant improvement that had occurred in fine and coarse wrinkling and skin texture during our original study was sustained, despite reductions in dose or frequency of application of tretinoin. The number of discrete lentigines decreased by 71% compared with the number before therapy. Histologic findings included a statistically significant thickening of the epidermis. Side effects were limited to a cutaneous retinoid reaction that diminished as therapy proceeded.