The administration of 8 - methoxypsoralen combined with UV-A exposure (PUVA) was found to be effective in a case of progressive pigmented purpuric dermatosis (PPPD). After one month (16 therapeutical sessions), favourable cleaning occurred in the skin areas clinically affected by purpuric lesions. Histological examination after the intensive phase of PUVA therapy showed decreased masses of the extravasated erythrocytes formerly situated around the dermal capillaries, and diminution of hemosiderin deposits. In addition, the inflammatory infiltrates were less intense following the maintenance phase of therapy. Various theories concerning the mode of action of oral photochemotherapy in PPPD are discussed in the light of these observations. This is the first report of a case of PPPD which was successfully treated by PUVA.