Forty patients with severe psoriasis (greater than 50% body surface area affected) were randomly distributed into three groups. Group I treated by haemodialysis, group II treated by peritoneal dialysis, and group III treated by modified Goeckerman treatment. Skin biopsies and blood samples were obtained before and after treatment. Skin biopsies were examined by direct immunofluorescence for IgG, IgA, IgE, IgM, C3 and C4 deposits. Trace metals (zinc and copper) concentrations were determined in plasma and skin tissue. Statistical analysis of the data obtained following ten dialysis sessions showed better response in peritoneal than haemodialysis, and both were better than Goeckerman treatment. This was insignificant as to the degree of improvement, but definitely significant as to the duration of remission induced. There were no important changes in plasma and tissue zinc and copper, yet there was significant decrease in IgG deposits after treatment in the three groups examined. We have concluded that dialysis treatment is a good therapeutic modality, especially for those with severe lesions in whom mortality and morbidity are high, especially if there is a contraindication to the other potent therapeutic modalities such as methotrexate.