The lanthanum modified lead zirconate titanate (PLZT) ferroelectric ceramics, considering La/Zr/Ti ratio of 8/60/40 and vacancies in A or B sites of the perovskite structure, have been analyzed by using X-ray diffraction, dielectric response, polarized light microscopy and ferroelectric hysteresis. No remarkable differences are observed between samples with A or B vacancies from the X-ray diffraction patterns and ferroelectric hysteresis loops. However, the dielectric measurements have revealed a significant decrease in the maximum values for the real part of the dielectric permittivity and an enhancement of the relaxor behavior in the systems where A vacancies have been considered. On the other hand, the anomalies observed in the temperature dependence of the remanent polarization suggest a frozen out in the dynamic of Nanometric Polar Regions (PNRs) around the same region of temperatures for both samples.