Attempts have been made to impart oil resistivity to the surface of nonpolar ethylene-propylene-terpolymer rubber by gamma radiation grafting of methyl methacrylate (MMA) monomer onto this rubber using a simultaneous technique. The effect of monomer concentration on the graft level has been studied. Grafted samples have been characterized using attenuated total reflectance infrared, scanning electron microscopy, energy dispersive X-ray analysis, and optical microscopy. The oil resistivity of the modified vulcanizates has been evaluated and compared with that of nitrile rubber. The effect of multifunctional acrylates on the grafting behavior of this monomer has also been studied.