In this study, we examined the effects of gamma irradiation on the mechanical, thermal, structural, and electrical properties of polyacrylonitrile (PAN). Irradiation doses of 20, 40, 60, 80, and 100 kGy were used, with non-irradiated PAN films serving as control samples. Micro-hardness measurements, mechanical tests, Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry analysis, color determination, X-ray diffraction, and electrical properties were investigated to evaluate the effects of the irradiation treatments on the PAN films. A fair consistency was observed between the microhardness results. Irradiation caused a significant deterioration in the mechanical properties of the samples. The tensile strength and percentage elongation at break decreased with increasing irradiation dose. Similarly, Young's modulus and toughness also decreased with increasing irradiation dose. The melting and crystallization temperatures decreased, whereas the degree of yellowness increased with increasing irradiation dose. The percentage crystallinity of the PAN film increased with increasing irradiation dose. The FTIR spectra showed that there was a tendency toward a greater effect of 7 irradiation on the structure of PAN at higher irradiation doses. The values of the electrical parameters, such as capacitance in parallel, dielectric constant, dielectric loss, resistance in series, resistance in parallel, reactance, and quality factor, increased, whereas the values of capacitance in series, impedance, conductance, susceptance, admittance, and phase angle decreased because of the gamma irradiation. (C) 2008 Wiley Periodicals, Inc. J Appl Polyrn Sci 110: 2569-2578, 2008