A case of hereditary neuropathy with liability to pressure palsies is described. The main histological findings in sural nerve were focal thickenings of myelin-"sausages", "tomaculae"-and wide variability of internodal length. Numerous fibers with signs of remyelination were present, while there was little evidence of active demyelination. There were moderate axonal changes. Electrophysiological study revealed slowed conduction velocity in peripheral nerves. The possibility of a congenital myelin defect in this disease is discussed.