Creep and stress-relaxation of linear low-density polyethylene (LLDPE) crosslinked with beta-irradiation was studied as a function of irradiation dose. It was shown that both storage modulus and alpha-relaxation are influenced by irradiation. An influence of relatively low gel content on stress relaxation was detected. However, the creep results showed an increase of the creep strain when the polymer is irradiated with a dose below 4 Megarad (MR) in comparison with a nonirradiated film. This increase corresponded to the disorientation in the amorphous phase, which takes place as a result of the film heating during irradiation. This disorientation was demonstrated by differential scanning calorimetry (DSC) and X-ray analysis. (c) 2006 Wiley Periodicals, Inc.