Clinical, cerebrospinal fluid and nerve biopsy findings from eight patients with peripheral nervous system complications of Lyme-Borreliosis are reported. Five cases showed the typical features of the Garin-Bujadoux-Bannwarth syndrome (meningoradiculoneuritis), one patient had a multiple mononeuritis associated with acrodermatitis chronica atrophicans Herxheimer. Two cases could not be classified under these diagnostic categories. In all patients we observed a prompt relief of signs and symptoms after antibiotic treatment. Nerve biopsy studies showed gross infiltrations of epineurial vasa nervorum and small infiltrations around endoneurial capillaries. The infiltrations consisted of lymphocytes, histiocytes and plasma cells. We did not find necrotizing changes of the vessel walls, but thrombosis and recanalization was observed in some epineurial vessels. Seven biopsies showed a significant loss of myelinated axons due to axonal degeneration. Only in one biopsy did we observe segmental demyelination next to axonal degeneration. We conclude that the PNS complications of Lyme-Borreliosis in early and late stages of the disease are angiopathic due to vasculitis of the vasa nervorum and primarily caused by axonal degeneration.