Hypertrophic neuropathy is a non-specific consequence of repeated demyelination and remyelination, encountered in a wide range of inherited and acquired disorders. We report an 11-year-old boy with HMSN III, a kind of hypertrophic neuropathy, with clinical, electrophysiologic and pathologic data. The electrophysiologic studies show complete conduction block in the upper and lower extremities with severe abnormal spontaneous activities. The pathologic findings of sural nerve reveal prominent hypomyelination, onion bulb formation, and severe endoneurial collagenization. Complete conduction block with the preservation of fair to good grade muscle strength is an unusual finding in hypertrophic neuropathy and other peripheral neuropathies, in general.