Nb2O5-modified PZT/ZnO nanowhisker (denoted as PZT/ZnOw-Nb2O5) piezoelectric composites were prepared by a solid state sintering technique. Effects of Nb2O5 addition on the microstructure, electrical, and mechanical properties of the PZT/ZnOw composites were investigated. With increasing Nb2O5 content, the grain size of the composites was reduced and the fracture mode changed from intergranular to intragranular gradually. Compared with the PZT/ZnOw composites, the dielectric, piezoelectric, and ferroelectric properties of the PZT/ZnOw-Nb2O5 composites were improved significantly, while mechanical properties were enhanced slightly. The optimum electrical and mechanical properties were achieved for the PZT/ZnOw composites modified with 0.75 wt% Nb2O5 sintered at 1150 A degrees C, with dielectric permittivity epsilon(r), piezoelectric coefficient d (33), planar electromechanical coupling k (p), remnant polarization P (r), fracture toughness K (IC), and flexural strength sigma(f) being on the order of 4930, 600 pC/N, 0.63, 29.2 mu C/cm(2), 1.56 MPa m(1/2) and 130 MPa, respectively. The Nb2O5-modified PZT/ZnOw piezoelectric composites, with comparable electrical properties and improved mechanical properties than those of commercial PZT-5H ceramics, are promising candidates for further applications.