Pb(Zr, Ti)O-3 (PZT) and Pb(Zr, Ti, Nb)O-3 (PNZT) thin films have been deposited on platinized silicon substrates by sputtering followed by a postannealing treatment. The Nb concentration in the films varied between 1 and 7 at. % with increments of 1 at. %. The effects of Nb modification on the piezoelectric response, and particularly on the longitudinal piezoelectric coefficient d(33), have been investigated. The introduction of Nb enhances the dielectric and piezoelectric properties of the PZT films. The best doping level ranges from 1 up to 2 at. %. The relative dielectric constant epsilon(r), reaches 1100, and the maximum value of d(33) is equal to 115 pm/V for a 1 at. % Nb-doped PZT in comparison to 820 and 55 pm/V for an undoped PZT film. PNZT films are suitable for microsystem applications. (C) 2000 American Institute of Physics. [S0003-6951(00)03422-7].