Grafting of vinyl acetate (VAc), 2-hydroxyethyl methacrylate (HEMA), and their binary monomer onto poly(tetraflouroethylene-perflourovinyl ether) (PFA) copolymer films was performed by means of gamma rays from Co-60 using the direct method. The factors affecting the grafting yield such as type of solvent, inhibitor concentration, monomer and comonomer concentrations, comonomer composition, and irradiation dose were investigated. It was found that the magnitude of the enhancement depends on the VAc/HEMA ratio in the comonomer feed solution; the grafting yield was higher when VAc-rich comonomer feed solution is used. The TGA analysis indicated that the copolymerization grafting of VAc/HEMA binary monomers onto PFA matrix improves the thermal stability. The results obtained in this study suggest that PFA-g-p(VAc/HEMA) copolymers have the potential to be used as blood-contacting devices in a broad range of biomedical applications. (C) 2011 Wiley Periodicals, Inc. Adv Polym Techn 30: 21-32, 2011; View this article online at wileyonlinelibrary.com. DOT 10.1002/adv.20204