The infrared spectra of poly(ethylene terephthalate) γ-irradiated in presence of organic solvents were recorded over the spectral region 200–300 cm−1. The analysis of these spectra showed that the combined effect of solvent and γ-irradiation results in appearance of two strong bands at 1550 and 1630 cm−1, increase in the intensities of the gauche bands at 1450 and 1370 cm−1and decrease in the intensity of the trans-band at 1340 cm−1. The aromatic ring C=C stretching band at 1410 cm−1was also affected. The profound spectral changes were observed only in samples irradiated in presence of solvents and were not observed in samples treated with solvents or only irradiated in atmosphere of air, these spectral changes were attributed to the changes in the intermolecular of intramolecular forces as a result of penetration of solvent molecules in the polymer and the ionizing effect of γ-iffadiation. It was found that the extent of the intensity variations depends on the nature of the solvent.