Expression of low-affinity neurotrophin receptor (p75NTR) was immunohistochemically examined in the peripheral nerve trunks, dorsal root ganglia, sympathetic nerve ganglia and spinal cords in various human neurological diseases manifesting peripheral neuropathies. p75NTR was expressed in the nerves with axonal degeneration, and was also prominent in the nerves with newly regenerating axons. In contrast, axonal pathology tended to reduce the expression of p75NTR in the neuronal perikarya of the dorsal root ganglion and sympathetic nerve ganglion neurons. In the ventral and lateral horn cells, the p75NTR immunoreactivity was not detected in the normal and diseased nerves except for amyloid polyneuropathy. These p75NTR expressions in the diseased human peripheral nervous tissues would be regulated by an underlying pathology-related process, and could play a role in peripheral nerve repair.