ur study examined changes in the red blood system of rats under the influence of aluminium chloride administered in a physiological way with drinking water in the following doses : 0.5 g/l, 1 g/l and 2 g/l. The significant decrease of erythrocyte numbers, haemoglobin levels and haematocrit values which accompanied the highly significant statistical elevation in reticulocyte contents were observed in intoxicated animals. Also, the decrease of mean cell volume (MCV), average diameter of erythrocyte (D) and its surface area (S) were noted. Respiratory surface of blood volume unit (S_resp.) and coefficient F in group received AlCl₃ at doses of 0.5 g/l were slightly higher then in control group. Groups that received 1 g/l and 2 g/l decreased in S_resp. and coeficcient F. Our data showed that aluminium intoxication impairs respiratory function of the blood.