The waste newsprint paperswere collected from local market  and submitted to chemical pulping in a kneader with 2M NaOH. The fiber after getting rid of water, treated again using 2M HCL solution for the same time period. Then the news print pulped microfibers (NPMF) batch obtained was mixed with Ethylene propylene diene monomer rubber (EPDM) on roll mill with differnet contents ranged from 5 to 50phr (part per hundred part of rubber). The prepared composites subjected to gamma irradiation at different doses from 20 up to 100kGy. The characterization of the microfibers carried out by different tools like scanning electron microscopy (SEM), X-ray diffraction (XRD),Forrier Transform Infrared spectra (FTIR) and Thermogravimetric analysis (TGA). The mechanical properties of prepared composites like tensile strength (Ts), Elongation at break (E_b%), tensile modulus(M₁₀₀) , tensile toughness and crosslink density (Cd) were measured as a function of fiber contents and irrdaition dose. The results indicated the Ts was increased with increasing fiber content up to 10phr and incresed with increasing irradiation dose up to 40kGy, while E_b% decreased by fiber content and irradiation dose. M₁₀₀ and Cd were incresed with invreasing fiber content up 50phr fiber and increased by irradiation dose up to 60kGy. The results concluded that toughness values of EPDM/ news print fiber composite reach maximum using 10phr fiber concentration and 60kGy irradiation dose.