A new process was developed to fabricate electrically conducting nylon 6/graphite nanocomposites via intercalation polymerization of epsilon-caprolactam in the presence of expanded graphite. The transition from an electrical insulator to an electrical semiconductor for nylon 6 occurred when the graphite volume content was 0.75, which was much lower than that of conventional conducting polymer composites. The electrical conductivity reached 10(-4) S/cm when the graphite content was 2.0 vol %. The TEM microphotographs suggested that the low percolation threshold and the great improvement of electrical conductivity could be attributed to the high aspect ratio (width-to-thickness), the high expansion ratio in c axis of the graphite sheets and the homogeneous dispersion of the nanoscale graphite particles in the nylon 6 matrix.