Lyme borreliosis, multisystem disease, when involve neurologic system is named neuroborrelosis. Symptomatology of neuroborreliosis is rich and various. Difficulties in recognition are connected usually with long period from tick bite to late neurological signs. Any headache and psychiatric disorder in the course of Lyme disease could be an early manifestation of invasion of the CNS by the spirochaetes. Each part of neurologic system could be involved. The most common clinical picture of neuroborreliosis is meningitis with cranial or peripheral neuropathies connected with radiculalgia, less common are encephalitis and myelitis, neuropathies and polyneuropathies, encephalopathies. Encephalomyelitis is the most serious form of neuroborreliosis. From the pathophysiologic point of view all cranial and peripheral neuropathies are forms of mononeuritis multiplex. Vasculitis and autoimmunology processes are present. Encephalopathy is due to neuroimmunomodulators, like lymphokines and by toxico-metabolic effect could be connected with each form of systemic borreliosis. Spheroplast L-form of borrelia could be responsible for difficulties with their eradication. Diagnosis of neuroborreliosis is based on culturing of B. burgdorferi from CSF, detection of specific antispirochaetal antibodies produced in subarachnoid space, detection of activated lymphocytes, other antigens detection in CSF (also after dissociation of complexes) or borrelial DNA sequences.