The biodegradation of new polymeric materials of natural origin and of their mixtures with other natural and synthetic polymers was investigated. The processes of biodegradation were carried out in an aqueous and a soil medium in the presence of air. Experiments with the biodegradation of cellulose carbamate showed that the product was more susceptible to biological decomposition than cellulose or its viscose derivatives. Experiments with the biodegradation of chitosan showed that the process was dependent on both the origin and properties of the samples, as well as on the degree of their deacetylation and conditions of the biodegradation process. Research into the biodegradation of mixtures of synthetic and natural polymers with the use of the method of light transmittance led to the general conclusion that the biodegradation process was largely dependent on the type the synthetic polymer as well as on conditions of the process.