In the paper below are presented the undesirable effects of aluminium in patients with chronic renal failure. Until now aluminum treatment has been used to reduce the level of phosphates in blood serum or in haemodialysis a this group of patients. The toxic activity is a result of cumulation of the element in organism, mainly owing to limited elimination through kidneys, but also as a consequence of disturbed absorption in digestive tract or intravenous infusion of blood serum and albumins. It can be expressed by several clinical syndromes, especially dialysis, encephalopathy, osteomalacia, microcystic++ anaemia, more rarely calcinosis and increased general morbidity and mortality rate. The diagnosis of suspected toxic activity of aluminium in patients with uraemia is based mainly on estimation of concentration of this ion in blood serum and aluminium deposits in skeletal system and skin. The effective treatment consist in intravenous infusions of deferoxamine in a dose 2 g 3 times a week for a long time.