Poly vinyl chloride (PVC) products are susceptible to biological attack. To study this problem, lignin was considered as a material in blend with PVC. Lignin is a renewable, naturally occurring compound and is obtained as a by-product of pulping processes. At present, extensive research has been performed to explore the utilization of lignin. This research studies the feasibility of partially replacing a copolymer of vinyl chloride-vinyl acetate (VC-VAc) by lignin in flooring formulations and evaluates the effects of lignin on the resistance of these formulations to fungi attack. The lignin utilized in the study was an organosolv lignin-Alcell lignin.  To accomplish the objectives, a series of PVC controls and PVC-lignin blends with various plasticizers were inoculated with fungi. After a 28-day incubation, the changes in chemical structure were analyzed by Fourie Transform Infrared (ATR/FTIR) spectroscopy. Optical stereomicroscopy and optical microscopy were employed to observe the changes at the surface.  This research is the original assessment of the resistances of PVC-lignin blends to biodegradation. After a series of experiments, it was found that all fungi species grew on every composite and showed similar abilities of growth. PVC and PVC-lignin blends are susceptive to fungi attack and plasticizers are the main targets of fungi attack; the susceptibility of the plasticizers to biodegradation in descendent order is: Di-ethylene glycol di-benzoate ( Benzoflex 2-45 ) > Alchil sulphonate ( Mesamoll ) > Di-octyl phthalate ( DOP ) > Tricresyl phospate ( Lindol ).  Lindol is the most suitable plasticizer for the formulation of PVC-lignin flooring; Alcell lignin is biodegradable; the presence of Alcell lignin in the complex interactive system PVC-lignin-additives increases the biodegradability of polymeric materials.