Measurements of changes in permittivity, tanδ, andd∂∂as function of compressive stress parallel to the polar axis are presented for lead zirconate—lead titanate transducer ceramics. The “hard” ceramics (PZT‐4 and PZT‐8) suitable for high‐power application show large changes of properties for stresses to 20 kpsi, but have good recovery on release of stress. The “soft” donor‐doped ceramics (PZT‐5A and PZT‐5H) suitable for detector applications show serious degradation with successive stress cycles. However, for peak stress below about 10 kpsi, their variation of properties and hysteresis within any cycle are less than those of the hard ceramics. Permittivity and tanδ of all these ceramics increase with increase of ac electric field. For the soft ceramics, the tanδ increase is great enough to eliminate their consideration for uses where efficiency or cool operation are necessary. High ac electric fieldcombinedwith compressive stress reduces these detrimental increases for the soft ceramics and increases them for the hard ceramics. Nevertheless, the hard ceramics remain far superior for high‐power high stress uses, with PZT‐8 being superior to PZT‐4.