We applied the “living” radical polymerization including stable free radical polymerization (SFRP) and atom transfer radical polymerization (ATRP) to controlled graftings. First, we address a “living” grafting to polyethylene (PE) and polypropylene (PP) by a combination of radiation-induced grafting and SFRP. Second is a “living” grafting of MMA to PE and PP by a combination of radiation-induced grafting and reverse ATRP with iron catalyst. Third is a “living” grafting of MMA to the functionalized high density PE with nicked-mediated ATRP and iron- mediated ATPR. In all cases, graft polymers grew in a living fashion. The graft polymer chains had the nearly identical characteristics of free polymer chains that produced from free initiators during grafting period. This is an advantage to utilize the free polymers as indices of grafted polymers if the characterization of the graft polymer is difficult. The slight difference of the characteristics between graft and free polymers is caused by a slightly different local concentration of monomer or catalysts around the propagating ends of grafted polymer from free polymer. The polymeric peroxides generated by radiation act as initiators and their initiation efficiency was determined to be around 60 – 70% that is consistent with the efficiency of the low molecular weight peroxides such as benzoyl peroxide, cumene peroxide, and di-tert-butyl peroxide when the peroxides were used in “living” polymerizations. These techniques were expected to control a precise structure of grafted materials.