Even at low content, polypropylene significantly worsens mechanical properties of the recycled PVC composite, i.e. tensile strength at break and elongation at break. But, if small quantities of surface modified nanofiller calcium carbonate is added, an applicable composite that contains 10-30% of waste material can be made. It was determined that nanosized calcium carbonate lowers melting point of polypropylene, perhaps by changing its crystalline form and has no influence on thermooxidative degradation of poly(vinyl chloride). Addition of nanofiller slightly lowers the surface free energy of the composites what is more prone when the low content of polypropylene is present. The recovery of tensile strength and elongation at break occurs and those properties reach the highest value at about 6% of CaCO3.