The effects of γ-irradiation on ethylene vinyl alcohol copolymer (EVOH) were investigated. Oxygen permeability decreased as irradiation dose increased in non-oriented (EF-CR), biaxially oriented (EF-XL) EVOH, and nylon/EVOH/PP. Irradiation increased tensile strength (TS) and elongation at break (%E) of EF-CR; whereas, TS of EF-XL was not significantly changed and %E of EF-XL decreased. Irradiation had no effect on TS and %E of nylon/EVOH/PP. Four volatile compounds, ε-caprolactam, 2-propyldecanol, 2-butyloctanol, and 2,3-diethyl-2,3-dimethyl-1,4-butanediol, were detected after irradiation. Optical properties were not changed.