The research aims to use shells powder as a filler adding to natural rubber with different amount (20,30,50,100,120,150 pphr) and observe its effect on mechanical properties of rubber which includes hardness and tensile strength . The obtained results from mechanical tests shown improved in rubber hardness after adding shells powder and increasing this property with increased percentage of powder ,but tensile strength increased to (20 pphr) and then strongly decreased after this percentage as shown in figures