This study evaluates the benefits of a potent and midstrength topical steroid compared with simple lubricating agents when used in combination with erythemagenic doses of sunlamp fluorescent UV irradiation in psoriasis. Twenty-six patients were studied in a bilateral symmetrical comparison. No significant differences were observed between topical corticosteroids and lubricants in the number of patients achieving a 75% or greater resolution of psoriasis. Topical corticosteroids did not reduce the number of treatments required for clearing. We did not observe faster recurrences in sites treated with topical corticosteroids. More severe burns and slightly less effectiveness were noted in patients irradiated five times weekly compared with three.