Low density polyethylene (LDPE) sheets were modified by radiation-induced graft copolymerization of N-vinyl pyrrolidone (NVP) and acrylonitrile (AN) binary comonomer of different molar ratios. The factors affecting the radiation modification process were optimized. The radiation-modified LDPE sheets were further modified via the chemical treatment of the grafted nitrile groups with thiourea. The modification processes were confirmed by FTIR and the modified LDPE sheets were characterized by studying their swelling behavior. The protein adsorption ability of the modified LDPE sheets was examined towards creatinine, as protein derivative and gamma-globulin fraction (II). Adsorption kinetics were calculated and possibility of selective adsorption was evaluated.