Graft copolymers of acryloylchloride (AC) with polyethylene (PE) and polyethyl eneterephtalate (PET) have been synthesized by grafting of AC from the vapor phase under mutual gamma-irradiation. It has been shown that both the amount of grafted reactive chains and their structure was determined by the polymer : monomer ratio and the total irradiation dose. The high grafting degree of reactive groups and their ability to interact with free amino groups of biological molecules both in organic media and in water solutions make these functionalized polymers suitable as reactive carriers for covalent immobilization of various amino groups containing compounds.