We report the findings in five muscle and three sural nerve biopsies,and in on e post mortem plexus specimen, from six patients with hereditary neuralgic amyot rophy (HNA). We found that the sensory nerves are definitely involved in HNA des pite the mainly motor symptoms, and that lesions in nerves and muscles are more wide spread throughout the peripheral nervous system than clinically presumed, b ut, simultaneously, very focally affect isolated fascicles within individual ner ves. We report the findings in five muscle and three sural nerve biopsies, and in on post mortem plexus specimen, from six patients with hereditary neuralgic amyot rophy (HNA). We found that the sensory nerves are definitely involved in HNA des pite the major motor symptoms, and that lesions in nerves and muscles are more wide spread throughout the peripheral nervous system than clinically presumed, b ut, simultaneously, very focally affect isolated fascicles within individual nerves.