The electrical properties of mica-polystyrene composites were studied using the impedance measurements technique. The study was carried out as a function of frequency and mica concentration. It was observed that the AC conductivity and the dielectric constant are increased with increasing of the mica content in the composite. The observed electrical results fit approximately the reported empirical equations concerning the AC conductivity and dielectric behavior of polymer composites. Relaxation processes were observed to take place for composites having high mica concentration. The observed relaxation and polarization effects of the composite are mainly attributed to the dielectric behavior of the mica filler. However, the results were explained on the basis of the interfacial (space-charge) polarization, dipolar polarization and decrease of the hindrance produced by the polymer matrix.