Degradation product patterns and morphology changes are demonstrated to be means by which to differentiate between physical/chemical (abiotic) and biological (biotic) ageing of degradable polymers. Comparison is made between low-density polyethylene (LDPE), LDPE + 7.7% starch and LDPE + 20% (starch + pro-oxidant). Pro-oxidized samples were subjected to aqueous sterile and aqueous biotic (Arthrobacter paraffineus) environments at ambient temperatures for 15 months, and thermo-oxidation at 95 degrees C in water. Carboxylic acids were identified in the abiotically degraded samples in contrast to the biotic environment, where assimilation of lower molecular weight products, especially carboxylic acids, had taken place as determined by gas chromatography and gas chromatography-mass spectrometry. Several hydrocarbons (C-C) were also present in these samples. This is in agreement with the proposed biodegradation mechanism of LDPE. The morphology changes, as monitored by X-ray diffraction (XRD) and scanning electron microscopy, were different in the two environments. A decrease in lamellar thickness (l) was demonstrated for biotically degraded LDPE + 20% (starch + pro-oxidant), while the corresponding abiotically aged samples showed a constant or increased value of l. The crystallinity (XRD-w(c)) for samples aged at ambient temperature showed that prolonged exposure to A. paraffineus resulted in decreasing value of w(c). In the accelerated environment, however, a constant increase in XRD-wc was monitored. The principal difference between abiotic and biotic degradation of polymers is that micro-organisms use polymers to gain energy. This is manifested as different degradation product patterns (reflecting degradation mechanisms) and a decreasing value of crystallinity and lamellar thickness with time. The abiotic degradation breaks bonds and releases degradation products, leaving the remaining polymer rearranged with a higher degree of order.