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AIMS A subset of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is characterized by the presence of anti-neurofascin 155 (anti-NF155) autoantibodies. In this paper, we investigated an anti-NF155 CIDP patient via clinical, electrophysiological, and neuropathological tests. MATERIALS AND METHODS The patient was a 15-year-old Chinese boy affected by distal limb weakness and tremor for a 6-month period. The patient was positive for serum anti-NF155 antibodies, high cerebrospinal fluid protein levels and symmetric hypertrophy of lumbosacral roots in MRI. Elongation of distal and F-wave latencies and decrease of compound muscle action potentials in motor nerves were recorded. Sensory nerve action potentials were absent. He accepted sural nerve biopsy. RESULTS Sural nerve biopsy demonstrated the typical pathological change of loss of transverse bands with mild detachment of terminal myelin loop from axon at the paranode. Some thin myelinated fibers and axonal degeneration were recorded. Besides, we found some myelin balloon formations with compressed axons. CONCLUSION We suggest that antibodies against F155 might be responsible for axo-glial junction disruptions leading to the dissociation of myelin and axon. Both conduction block and axonal impairment contributed to the neuropathy in anti-NF155 CIDP.