Fatigue properties induced by cyclic electric loading in PLZT capacitors incorporating zirconia were investigated. The improvement of fatigue properties was achieved with increasing the amount of incorporated zirconia. During the fatigue process, the onset of fatigue, which is characterized by the fast decrease of switchable polarization, was delayed in composite PLZT/zirconia, compared to the monolithic PLZT samples. After about 10(6) polarization reverse cycles in composite samples, the capacitors seemed to show no sign of deterioration in saturated or remanent polarization. A higher resistivity was observed in the PLZT/zirconia compared to monolithic PLZT ceramics during the measurement of complex ac impedance spectroscopy. According to the dynamic behavior of oxygen vacancies during the electric switching process, the mechanism of enhancement of the fatigue properties was attributed to the low content of oxygen vacancies in bulk ceramics and less pinning effect to ferroelectric domain walls.