The plasticized poly(vinyl chloride) (PVC-P) and its blend with cellulose (PVC-P/cell) were prepared by means of extrusion. The samples were then biodegraded in forest soil as well as in soil enriched with cellulolytic microorganisms. Moreover, the samples were vaccinated with chosen species of fungi whose direct effect on polymer was then observed. The course of biodegradation was monitored in terms of, and by means of the following: weight loss, carbon dioxide evolved, attenuated total reflectance infrared (FTIR-ATR) spectroscopy, gel permeation chromatography (GPC), as well as visual and microscopic observation (OM, SEM). The mechanical properties of samples were studied using the standard tensile tests. It was found that biodegradation in soil occurs in PVC-P and this process is accelerated in the composition of PVC-P with cellulose. The biodecomposition yield of PVC-P/cellulose blends (calculated as relative percentage weight loss) is several dozen times higher than that of PVC-P. (c) 2007 Wiley Periodicals, Inc.