In the case of the insulation polymeric materials, such as polyethylenes, it is of essential interest to understand correlations between structural changes and (di)electric properties. The dielectric behavior of different polyethylenes, low density polyethylene (LDPE), linear low density polyethylene (LLDPE) and high density polyethylene (HDPE), irradiated to different absorbed doses of gamma radiation, was studied through dielectric loss (tan delta) analysis. Dielectric relaxation behavior is related to the changes in the initial structure of different polyethylenes and to the radiation-induced processes of oxidative degradation and crosslinking. Differential scanning calorimetry (DSC), IC spectroscopy and gel measurements were used to determine the changes in the crystal fraction, oxidative degradation and degree of network formation, respectively. (c) 2005 Elsevier Ltd. All rights reserved.