Modification of polymers is widely used nowadays. Among the most important and practical methods of modifying polymers is blending. Ethylene propylene diene monomer (EPDM) was blended with low density polyethylene (LDPE)in five different ratios for each (100/0, 90/10, 80/20, 70/30, and 60/40) respectively with loading the blends with carbon black filler. Effect of polyethylene content in the blend on its swelling behavior and Mechanical properties was investigated. The critical content of PE in the blend was 0.3 weight fraction. All the blends showed excellent swelling behavior in sea water medium. It was found that addition of PE into EPDM matrix enhances the mechanical properties of the blends such as: tensile strength and modulus of elasticity .Also EPDM/PE blends show sufficient degree of toughness to be utilized in industrial applications efficiently.