Biodegradation is a process of plastic decompositioning by microorganisms, with final products which include carbon dioxide, methane, water, inorganic salts and biomass. Some of the biodegradation ways include surface changes and loss of structural strength, assimilation by microorganisms, enzymatic degradation, gradually tearing of the main chain and weight reduction. The mechanism of biodegradation process includes dissolution, hydrolysis and enzyme catalysed reactions of decomposition. Methods of biodegradation are degradation in soil, sludge anaerobic digestion, degradation in pure culture and composting. The final product of decompositioning is biologically stable product. Polymer properties that affect the biodegradation process are surface properties (hydrophilicity/hydrophobicity), the primary chemical structure, secondary structure (melting temperature, elasticity), mobility, presence of plasticizers and additives, presence of the side chains, molecular weight and crystallinity. Objectives of biodegradation are reducing accumulation of plastics in landfills, lowering the levels of CO2 which pollutes the atmosphere and reducing amount of soil toxic compounds contained in a plastic polymer material.