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Graft copolymerization of acrylic acid/acrylonitrile (AAc/AN) comonomer onto low-density poly(ethylene) (LDPE) and poly(ethylene terephthalate) (PET) films using direct radiation grafting technique has been investigated. The effect of different reaction conditions on the grafting yield was studied. The structure of the grafted films at different compositions was characterized by FTIR, TGA, SEM, and XRD. Biodegradation of grafted LDPE and PET was investigated by burial method in two types of Egyptian soils (agricultural and desert soils). The bacteria responsible for biodegradation were isolated and characterized, and the capacities for the growth on these polymers as substrates were compared. The isolates from agricultural soil were characterized as Pseudomonas, Alcaligenes, Bacillus, Proteus, and Enterobacter, whereas the isolates from desert soil were characterized as Alcaligenes, Bacillus, and Pseudomonas.-The highest degradation rate was found to be achieved using agricultural soil. It is found that the isolated strains belonging to the genus Pseudomonas were mainly responsible for the degradation of both polymers. It has also been found that the increase of AAc ratio in the composition increases the hydrophilicity of the films and the degradation rate. PET polymer is generally found to be more resistant to the biodegradation than LDPE in the two types of soils tested. (C) 2007 Wiley Periodicals, Inc.