Some peculiar features were studied for radiation grafting of monomers of various structures and reactivities in radical polymerization onto polyolefins (polyethylene and polypropylene). From the point of view of the kinetics and mechanism of grafting, the monomers are divided into two classes: The first class includes all monomers active in radical polymerization. When irradiated together with the polymeric matrix, they are grafted onto it as long polymeric chains and parallel to this occurs homopolymerization. The second class includes nonactive or slightly active monomers for radical polymerization. They are characterized by the formation of single units or short grafted chains. The possibility to add nonactive monomers with high radiation chemical yields was demonstrated. A mechanism was proposed to explain high radiation yields for a number of nonactive monomers by transferring the radical state along and/or between polymer macromolecules.