The effect of Cu nanoparticle (NP) content (0.3-3.0 wt%) on antibacterial, thermal, and rheological properties of PVC composites prepared by melt blending method was investigated. The composites were characterized by scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), capillary rheology, thermogravimetric analysis (TGA), and inductively coupled plasma atomic emission spectroscopy (ICP-OES). A homogeneous distribution of copper on the composite surface was observed by SEM-EDX. TEM images of Cu NPs/PVC composite films showed well-dispersed and distributed Cu NPs and microparticles in the PVC matrix, but the size of particles increased with increasing copper content. The shear thinning and power law behavior was observed for all samples. At low shear rates (100 s(-1)) apparent viscosity of composites with copper loading lower than 1.2 wt% exhibited a ball bearing effect. The Cu particles enhanced the thermal stability of Cu NPs/PVC composites compared with neat PVC. The release of copper ions from Cu NPs/PVC composite films into the aqueous medium was negligible after 6 h of immersion. Polymer films with Cu NP amount higher than 0.6 wt% showed a similar kinetics of bacterial growth; therefore, a substantial improvement of antimicrobial activity was not observed with increasing Cu NP content.