Acute and chronic syndromes of Lyme neuroborreliosis are recognized. Acute syndromes are clinically pronounced and comprise meningitis, neuritis of the cranial nerve, radiculoneuritis. Chronic syndromes are less evident. These are moderate encephalopathy and radiculoneuropathy. The diagnosis of the chronic syndrome is based on the presence of early classic signs of BL. CSF must be tested for routine procedure and in pair with serum in the test for selective accumulation of antibodies to Bb in the CSF. Neurophysiological studies help detect memory defects. Electrophysiological tests verify radiculoneuropathy. NMR investigation of the brain and SPECT-scanning may demonstrate damage to the white brain matter. We have much experience with i.v. administration of ceftriaxone (2 g/day for 4 weeks) which relieved neurological syndromes several months later.