The comparison of degradation of modified poly(e-caprolactone) film in different environments is presented. Poly(e-caprolactone) was incubated in a natural environment ± sea water (the Baltic Sea), in buffered salt solution, in liquid medium containing sea water with NaN3 and in compost with plant treatment activated sludge (under natural and laboratory conditions). The characteristic parameters of sea water and compost with active sludge are described. Their influence on degradation of modified poly(e-caprolactone) is discussed. Weight changes, viscosity, tensile strength, DSC parameters of melting and crystallization and changes in morphology of polymer surface were tested during the period of biodegradation. In liquid medium containing sea water with sodium azide and in buffered salt solution the slow hydrolysis process of poly(e-caprolactone) was observed. In natural environments the poly(e-caprolactone) film was completely assimilated after seven weeks of incubation. This means that poly(e-caprolactone) modified by slip and anti-block one additives was very sensitive to an enzymatic attack by microorganisms present in the Baltic Sea water and in the compost with activated sludge under natural conditions.