An AC electrical strength test campaign was performed on different Low Density Polyethylene (LDPE) nanocomposites. Such materials were obtained by the dispersion of inorganic nanoparticles having different aspect ratio and surface nature: silica AEROSIL 200 and montmorillonite. All the considered nanofillers have been organically modified in order to obtain a good dispersion and an efficient interfacial interaction.. The investigated nanocomposite materials show a higher electrical strength than the pure LDPE.