The dependence of some electrical properties of aluminum flake-epoxy composites on frequency and filler content is studied. The insertion loss as well as the shielding effectiveness (SE) show great dependence on filler concentration. The SE for the composites varies linearly with the microwave frequency and reaches up to 50 dB for a 90 wt.% composite specimen. The dependence of the electrical conductivity on the filler content shows that the composite changes from an insulating to a conductive behavior. The composite structure revealed by scanning electron microscopy supports the observed variations of the electrical conductivity.