This article describes electrically conductive polymer blends containing polyaniline-dodecyl benzene sulfonic acid (PANI-DBSA) dispersed in a polystyrene (PS) matrix or in crosslinked polystyrene (XPS). Melt blending of previously mixed, coagulated, and dried aqueous dispersions of PANI-DBSA and PS latices lead to high conductivities at extremely low PANI-DBSA concentrations (ϳ0.5 wt % PANI-DBSA). In these blends, the very small size of the PANI-DBSA particles and the surface properties (with surfactants used) of both the PANI and polymer particles play a major role in the PANI-DBSA particle structuring process. The PANI-DBSA behavior is characteristic of a unique colloidal polymeric filler with an extremely high surface area and a strong interaction with the matrix, evidenced by a significantly higher glasstransition temperature of the matrix. The effect of the shear level on the conductivity and morphology of the PS/PANI-DBSA blends was studied by the production of capillary rheometer filaments at various shear rates. An outstanding result was found for XPS/PANI-DBSA blends prepared by the blending of aqueous XPS and PANI-DBSA dispersions. Some of these blends were insulating at low shear levels; however, above a certain shear level, smooth surface filaments were generated, with dramatically increased and stable conductivities.