The crystallinity of linear low-density polyethylene (LLDPE) after electron beam irradiation and subsequent grafting with acrylamide in aqueous solution was investigated by differential scanning calorimetry and X-ray diffraction. The LLDPE was pre-irradiated in air or argon in the dose range up to 20 Mrad. The pre-irradiation atmosphere influences the grafting kinetics due to differences in the resulting morphology in the LLDPE. The cross-sections of the LLDPE film samples are grafted completely through before the final degree of grafting is reached, as analysed by scanning electron microscopy and scanning electron microprobe quantometry. The progression of grafting is related to a decrease in the degree of crystallinity and at higher graft yields also in the average crystallite size of the LLDPE trunk polymer. The difference in grafting behaviour of the LLDPE pre-irradiated in air or argon was investigated by comparing the decline in crystallinity in the material during grafting after the two types of pre-irradiation.