The role of oxygen pressure during the pulsed laser deposition of lead zirconate stannate titanates (PLZST) thin films was discussed. It was found that the oxygen pressure was in the range of 100-125 mTorr. The roughness of the films increases with increasing oxygen pressure. During deposition, fatigue and leakage current were also found to decrease with the oxygen pressure. The results show that for the samples deposited under higher oxygen pressure, there exist low-frequency dielectric dispersion process.