Rubber type materials are preferred because they are suitable for use in many engineering applications besides their elasticity . EPDM rubber show outstanding heat, ozone and weather resistance and has excellent electrical properties. Therefore this rubber as an elastomer is an engineering material that has wide range of applications in industry such as door and window seals, radiator, garden and heating hoses, tubing, washers, belts, electrical insulation, roofing membrane and rubber mechanical goods.In this works, the stress relaxation behaviour of EPDM rubber at the room temperature were experimentally investigated. Applied to the hardness EPDM samples were subjected to different loading programs. In addition, for the loading programs that were implemented, it is shown that for the EPDM rubbers tested the stress relaxation curves obtained at different stretch ratios may be represented by a single representative curve for the specimens having the same hardnesses.