One hundred and fifty out of 944 European dialysis centers reported experience with patients suffering from psoriasis. Ninety-three centers returned special questionnaires on 97 patients with end stage renal failure (ESRF patients) and on 49 patients dialyzed for psoriasis but who had normal renal function (NRF patients). Improvement of skin disease was reported in 17 out of 27 NRF patients according to both "objective criteria" and the patients' personal opinions. However, most of these patients had been on dialysis for less than one year (9.9 +/- 11.1 months) which is too short to allow for the spontaneous recurrence of psoriasis. In contrast, 60% of ESRF patients had been on dialysis for 45 +/- 3.1 months. Skin disease definitely improved in 20% of these patients after commencement of dialysis. This proportion is greater than the expected spontaneous long-term remission of psoriasis.