Graft copolymerization of methyl methacrylate and acrylamide onto ovalbumin was carried out with redox system with ceric ion. Initiation of grafting occurred very rapidly, and the number of grafting sites reached a maximum after about 2 min. regardless of initial ceric ion concentration. The grafted polymer chains were separated by selective hydrolysis of the protein backbone with hydrochloric acid or protease in order to characterize the graft copolymers. The grafted polyacrylamide separated by the proteolytic digestion contained a carbohydrate residue at the end of the polymer molecule. The problem of grafting sites on ovalbumin is discussed.