A case of a young man who presented symptoms and clinical signs of polineuropathy that occurred in connection with recurrent hypoglycemic episodes is reported. The hypoglycemia was probably caused by a pancreatic islet tumor. There were, symmetric weakness and wasting of hands and feet, absent tendon reflexes and 'glove and stocking' loss of sensation. Electromyographic studies showed denervation potentials with slight reduction of nerve conduction velocities. Sural nerve biopsy studied by optic and electronic microscopy showed axonal degeneration without signs of demyelination or remyellnation. There are only 30 similar cases reported in the literature. According to experimental findings, the authors believe that glucopenia is the mechanism responsible for the development of the neuropathy, and that at present time there is no evidence for a direct insulin effect.