Abstract: The effect of the ion-exchanging (chelating) agent EDTA on cadmium (Cd) toxicity and its impact on fish growth, food utilization, haematological and biochemical changes in Nile tilapia (Oreochromius niloticus) were studied. Fish (35-40 g) were exposed to 10 ppm Cd alone or with 0.1, 0.2 and 0.3 g EDTA L-1 for 15 and 45 days. Cd exposure reduced significantly (p< 0.05) the fish growth feed utilizations erythrocyte count (RBCs), haemoglobin content (Hb), haematocrit value (Hct), mean cell haemoglobin (MCH) and mean cell haemoglobin concentration. All these parameters were improved when EDTA was applied with Cd. The values of RBCs, Hb, Hct, MCH and MCHC increased significantly to be as in the control fish group. Significant decreases in alkaline phosphatase activity and total protein (TP) in plasma, muscle and liver also observed in fish exposed to Cd alone. However the plasma glucose concentration, total lipids (LP), aspartate aminotranseferase (AST), alanine aminotransferase (ALT) and acid phosphatase (ACP) increased significantly in fish exposed to Cd alone. Addition of EDTA to Cd contaminated medium enhanced biochemical parameters in fish and the enzyme activities returned to be as the control fish group. Addition of EDTA to Cd-contaminated medium considerably reduced metal absorption and its accumulation in fish tissues, while metal level increased in water and feces. Fish exposed to Cd alone accumulates 2.16 and 5.972 mg Cd g-1 dry weight in liver tissue after 15 and 45 days, respectively. Cd concentration was reduced significantly to 1.292 and 4.16; 0.94 and 3.79; 0.42 and 2.45 mg Cd g-1 dry weight tissue in fishes exposed to 0.1, 0.2 and 0.3 g EDTA L-1 after 15 and 45 days, respectively. Similar trends were observed in gills and muscle.