Crack-velocity (v-K) curves and crack-resistance (R) curves for unpoled ferroelectric and ferroelastic lead zirconate titanate (PZT) were determined for long cracks in compact-tension (CT) geometry using an in situ fracture device on the stage of an optical microscope. The steady-state crack length and the plateau value of R-curves measured at controlled constant velocities increased with increased velocity. The plateau value for 10(-6) m/s was 1.2 MPa(.)m(1/2) after 1.3 mm of crack extension and for 10(-4) m/s was 1.4 MPa(.)m(1/2) after 2.2 mm.