We studied retrospectively the cases of neurological forms of Lyme disease observed in two internal and two neurological departments from 1986 till 1993. Twenty five cases have been collected among 15 men and ten women whose mean age was 61 years. Tick bites were previously noticed in 11 cases. Erythema chronicum migrans (ECM) was mentioned in 16 cases mostly on lower limbs. The mean time between ECM and the onset of neurological symptoms was less than 1 month in 11 cases, 2 months in three cases, and 6 months in two cases. Neurological abnormalities were often associated in the same patient. Hyperalgic radiculitis (n = 16), mainly noticed in the ECM territory (n = 10) was only sensitive in six cases and associated with motor deficit in ten. Atypical polyradiculoneuritis was achieved in six cases. Clinical (n = 5) or biological (n = 22) meningitis could occur: CSF was clear with pleiocytosis (132 per mm3), mainly lymphocytic, and hyperproteinorachia (1.2 g/l) with normoglycorachia. An increase of the CSF immunoglobulins G with oligoclonal fragmentation was noticed in 11 cases. Cranial neuropathy was frequent: VII (n = 8), VI (n = 2), III, IV, VIII (n = 1). Encephalitis (with white matter demyelination) resolved partially in two cases. Diagnosis was always confirmed by Borrelia burgdorferi serology (indirect immunofluorescence) with a significant increase of the antibodies titer (n = 17) or a CSF titer > 1/4 (n = 11). Syphilitic serology was always negative. All patients were treated with parenteral beta lactamins and four with corticosteroids. Outcome was favorable in 20 patients with incomplete resolution of neurological symptoms in two patients.