Previous reports on neuropathy in Lyme disease and related disorders suggest predominant demyelination in most of the few cases investigated. We analysed retrospectively electrophysiologic data in 29 patients with MPN-GBB. In peripheral nerve involvement slowed NCV and/or prolonged DL was the prominent finding, concordant with primary demyelination. Distribution of pathology resembles mononeuritis. Facial nerve palsy was common and often bilateral.