The relationship and influence of varying Co-60 gamma-ray irradiation doses, in the range 0.77-5.2 MGy, on the morphology of polyethylene have been investigated using high-resolution solid-state C-13 nuclear magnetic resonance analyses through variation of different phase components, T-1cr T-2c relaxation parameters, and line width. The cross-linking in the irradiated polyethylene takes place mainly in the non-crystalline regions. However, distortion and damage to the folded chain of the crystal lattice are observed in the crystalline regions. For the interfacial phase, both cross-linking and distortion could occur. As a result, part of the crystalline component transformed into a non-crystalline one. It was also found that the orthorhombic crystalline lattice transformed into a monoclinic one within the crystalline phase in polyethylene under higher doses of irradiation.