Background: the release of heavy metals into the environment through industrial effluents is a major concern, worldwide and removal of such pollutants has been a great concern during the last decades. Heavy metals are not biodegradable and tend to be accumulated in organisms and cause numerous diseases and disorders. Aim of the Work: this study evaluated the protective role of synthetic zeolite against cadmium toxicity of freshwater crayfish (Procambarus clarkii). Patients and Methods: the crayfish was divided into six groups (36 individual in each group), the first group was used as a control group, the second group was exposed to a dose of (50 μg/L) cadmium chloride for 45 days, the third group exposed to a dose of (50 μg/L) cadmium chloride for 45 days and then added zeolite (1 mg/L) for 45 days. The fourth group was exposed to a dose of (50 μg/L) cadmium chloride for 45 days and then added zeolite (5 mg / L) for 45 days, the fifth group was exposed to a dose of (50 μg/L) cadmium chloride plus (1 mg/L) zeolite for 45 days. The sixth group was exposed to a dose of (50 μg/L) cadmium chloride plus (5 mg/L) zeolite for 45 days. After the experimental periods, the crayfish were weighted and hemolymph was collected to measure the biochemical parameters (Glucose, total protein, albumin, globulin, A/G ratio, cholesterol, triglyceride, LDL, HDL, Na+, K+, Cu+2, Ca+2and Mg+2). Results: in G2 the concentration of total protein, albumin, globulin, HDL, Na+, K+, Cu+2 and Ca+2 were significantly decreased (p< 0.05) compared with the control group, while glucose, A/G ratio, cholesterol, triglyceride, LDL and Mg+2 were significantly increased (p< 0.05) compared with the control group. The addition of the ion-exchanging agent, zeolite (1 mg/L and 5 mg/L) to cadmium exposed group (G2) caused improvement in weight and all hemolymph biochemical parameters in G3, G4, G5 and G6.  Conclusion: the synthetic zeolite was able to protect crayfish against cadmium toxicity by reducing the transfer of cadmium from polluted water into crayfish tissue and reducing the chance for metal uptake by interacting in the experimental medium which in evidently improves the physiological and biochemical functions.