The material comprises 10 cases with a history of Guillain-Barré syndrome within the last several years in which clinical investigations failed to demonstrate any abnormalities. Electrophysiological investigations of peripheral nerves including conduction velocity in motor fibres--maximal and minimal, sensory fibres, standardized terminal latency--showed presence of changes evidencing slight but persisting subclinical lesion to peripheral nerves, especially in subjects affected in early childhood. Slowing of conduction involved motor as well as sensory fibres in these nerves and was more pronounced in the ulnar nerve than in the remaining nerves (peroneal, axillary, musculocutaneous and facial).