Dielectric measurements in the frequency range (104 to 10-3 Hz) are presented for opaque PMN [Pb(Mg1/3Nb2/3)O3] hot-pressed ceramic samples. Equivalent results for transparent lanthanum-doped PMN and PMN (90%): PbTiO3 (10%) are also presented. Observation of “Anomalous Low-Frequency Dispersion” has new implications for the understanding of microstructure and transparency effects in these materials.