A uniaxial compressive stress significantly modifies the dielectric and piezoelectric response of Pb(Zr,Ti)O3 (PZT)-based piezoceramics. In soft PZT, the pre-stress decreases both the piezoelectric coefficient and its increment with increasing dynamical stress amplitude. However, an increase of both quantities is shown in hard PZT. Similar effects are observed in the dielectric response. It is proposed that the differences between such behaviors are due to the possibility of domain coalescence in the materials whose domain walls have high mobility. Furthermore, the enhancement of the response in hard PZT could be explained by change of the interaction energy between complex defects and domain walls induced by the compression.