Chronic, mentally subnormal epileptic patients were clinically and neurophysiologically studied in order to determine the occurrence and type of peripheral nerve dysfunction. We observed significant impairment of motor and sensory nerve conduction velocities and H-reflex latencies. Amplitudes of sensory and motor responses were diminished. Motor distal latencies were not prolonged. Conclusive EMG signs of active denervation were not observed. The possible role of anticonvulsive treatment as an underlying noxa is discussed.