The response of oriented poly(ether ether ketone) fibres to high energy electron radiation has been investigated by differential scanning calorimetry and wide angle X-ray scattering (WAXS). Absorbed radiation doses within the range 0-400 MGy have been considered. As the radiation dose increases, both the melting temperature and enthalpy of fusion decrease, and above 260 MGy no melting endotherm has been observed. However, the X-ray scattering behaviour indicates that these observations are not simply associated with radiation-induced crystallite destruction. Although the intensities of the crystalline reflections diminish with increasing dose, at 260 MGy the scattering curves appear only slightly changed from those of the unirradiated material. At higher doses, extensive modification of the scattering pattern does occur, but even at 400 MGy substantial remnants of the crystalline scattering peaks are evident. These results are interpreted in terms of the formation of crosslinks during irradiation which subsequently serve to modify the melting behaviour of the polymer extensively, but which do not disrupt molecular correlations (as sampled by WAXS) to the same extent.