This study was designed to detect possible changes in the immunocytology of the human immune system in the skin, cervix and peripheral blood of patients with chronic renal failure (CRF) treated by conservative methods, haemodialysis (HD) and continuous ambulatory peritoneal dialysis (CAPD). In the skin, Langerhans cell numbers were reduced in CRF, CAPD and HD patients but in the cervix, Langerhans cells were reduced only in the CRF patients. There was a preponderance of T suppressor lymphocytes compared with T helper lymphocytes in the epidermis in the CRF and the CAPD groups. The presence of natural killer cells in the epidermis of the renal groups compared to controls was significant in the CRF and HD patients while the presence of T suppressor lymphocytes in the epidermis compared to controls was significant only in the CAPD patients. In the dermis, there was a mixed cellular infiltrate of T helper and T suppressor lymphocytes but with no subset attaining significance. The dermal infiltrate of T helper lymphocytes in all three groups of renal patients was significantly reduced compared to controls. In CRF patients, peripheral blood pan T cells, T helper and T suppressor lymphocytes and B lymphocytes were reduced, while T suppressor lymphocytes were reduced in both HD and CAPD patients, compared to controls. Though the results confirm alteration of the immunocytology of the skin, cervix and peripheral blood, we could not relate them to a clinical finding.