Ageing of EPDM synthetic elastomers exposed to gamma-irradiation has been investigated using solid-state NMR Spectroscopy. Both C-13 high-resolution and H-1 wideline measurements were carried out to evaluate chemical degradation including oxidation products formation, chain scission and crosslinking phenomena. Highly specific structures were tentatively proposed as a result of careful examination of C-13 chemical shifts. The importance of diene monomer, the stabilising effect of curing process and the addition of antioxidants were evaluated on the basis of several polymer compositions. (C) 2003 Elsevier Science Ltd. All rights reserved.