In our previous study, we have investigated the biodegradation of ïÂ§-sterilized polyolefins in composting andmicrobial culture environments at different doses. It was found that the biodegradation increases with the increasing dose of ïÂ§-sterilization and time of incubation in compost. It was concluded that the pretreatment of ïÂ§-sterilization can accelerate the biodegradation of neat polymer matrix in biotic conditions significantly. The aimof the present study is to study the effect of ïÂ§-dose rate on the biodegradation of ïÂ§-sterilized polyolefins. Films of isotactic polypropylene, high density polyethylene and ethylene-propylene (EP) copolymer were sterilized under ïÂ§- radiation with doses of 10 and 25 kGy. Two different 60Co sourceswere used with dose rate 600 and 780 Gy h-1. Neat and sterilized samples were incubated in compost and fungal culture environments. The changes in functional groups, surface morphology and intrinsic viscosity in polymer chains were characterized by FT-IR spectroscopy, SEM and viscometric measurements, respectively. It was observed that both ã-degradation and biodegradation processes depend on the dose rate of ã-source. It was found that the biodegradation of ïÂ§-sterilized polyolefins in composting and microbial culture environments increases with decreasing the ïÂ§-dose rate.