This article describes the satisfactory clinical improvement obtained in the majority of a group of 72 patients with psoriasis of various types as a result of the oral and/or topical administration of 8-methoxypsoralen followed by long wavelength ultraviolet irradiation. The irradiation source used was that of conventional longwave UV fluorescent tubes mounted in a specially constructed cubicle. Until such time as the long term effect of this form of photochemotherapy on the cell has been evaluated and the most appropriate regime worked out, it would seem to be important to restrict the amount of irradiation used to that required to produce acceptable maintained clinical improvement.