Neurological manifestations are characteristic of stage 2 and stage 3 borreliosis. In stage 2, some 15% of the patients have neurological symptoms expressed as a triad of aseptic meningitis, cranial neuritis and radiculitis. Stage 3--chronic neuroborreliosis affects some 5% of untreated patients. The condition has its onset at the earliest 6 months after the infection, and is characterized by encephalopathic symptoms, such as fatigue, sleep and memory disturbances, and depressive states. Further manifestations of this stage may be Lyme polyneuropathy, in rare cases also progressive borrelia encephalomyelitis and cerebrovascular neuroborreliosis. The treatment of choice is intravenous administration of cephalosporins over 2-4 weeks. The success of treatment should be assessed on the basis of the clinical course rather than on laboratory results. Patience is required in the treatment of the post-Lyme syndrome, characterized by residual symptoms, recurrences or a relapsing course.