The aim of this study was to develop and verify the electrothermal atomic absorption method for aluminium determination in human serum and correlate the concentration of aluminium in serum of patients on dialysis and in water for preparation of dialysate. Two centres were included: centre A with accidentally enhanced concentration of aluminium in water for preparation of dialysate and centre B with very low water aluminium. Aluminium level in serum of healthy people was also analysed. The results showed that the analytical method was reproducible and sufficiently accurate in determining serum and water aluminium. Normal values obtained for aluminium in the sera of healthy people ranged from 0.9 to 12 micrograms/L and were significantly lower than all values obtained from the dialysis centre A. The aluminium concentration in serum of dialysed patients displayed linear correlation to aluminium concentration in water used for preparation of dialysate.