An alternative treatment modality for difficult to treat psoriatic patients is the combination of retinoids with broadband UVB (re-UVB). We have used re-UVB treatment to control psoriasis in some patients that could not be managed with single agent therapy, but these have been in individual patients outside of formal clinical trials. A small number of published studies have described clinical clearing of psoriasis with the re-UVB combination using fewer overall treatments compared to UVB therapy alone. No data are available to evaluate whether re-UVB produces longer disease remissions compared to UVB alone or whether long-term maintaince UVB treatment can be effectively accomplished by re-UVB (particularly using low doses of retinoids). From several previous clinical trials that we have conducted with retinoid monotherapy or UVB monotherapy, we hypothesize that the re-UVB combination may produce better and more durable clinical/pathological responses of psoriasis than single agent treatment. The combination therapy of acitretin and UVB phototherapy will be superior in clinical/histopathological efficacy compared to either agent used as monotherapy. Furthermore, re-UVB may prolong remission times compared to UVB-induced clearing and/or lead to more effective maintaince treatment with occasional UVB irradiation. Furthermore we postulate that re-UVB using 312 nm UVB may be the most effective therapeutic combination.