Polyethylene, cellulose and their blends with different compositions (5-30% cellulose content) were exposed to UV radiation or composted in soil for bio-degradation. Both types of degradation were carried out under laboratory conditions (room temperature, air atmosphere). The course of degradation processes has been studied using ATR-FTIR and Raman spectroscopies. There are practically no changes in spectra of photo- or bio-degraded pure PE films and cellulose powders. In contrast, the PE/cellulose blends are less stable than pure components and the processes of photodegradation seem to depend on blend composition and irradiation time. Prolonged UV exposure (100 h) leads to efficient photo-oxidation of blends studied. Biodegradation effect was also pronounced in PE films containing 30% cellulose. (c) 2005 Springer Science + Business Media, Inc.