We have treated seven patients with severe psoriasis with sham or true hemodialysis. Three patients received one 24-h course of true hemodialysis over 4 d followed by an identical 24-h course 4 weeks later. Four patients received one 24-h course of sham dialysis over 4 d followed by a 24-h course of true dialysis 4 weeks later. Significant subjective improvement was noted by both groups after the first series of treatments but not after the second. No objective improvement in skin disease was found at any time. We were unable to confirm the many uncontrolled reports on the efficacy of dialysis in ameliorating severe psoriasis. Neither the heparin used for anticoagulation, the acetate present in the dialysis bath, nor the removal of a “psoriatic factor” seemed to affect the skin disease in these patients.