11 patients with lymphocytic meningo-radiculitis (Bannwarth's syndrome) are described. The disease is characterized by intensive pain, often radiating and migrating, and neurological deficits, i.e. peripheral facial palsies, as well as disseminated radiculopathies. In 4 patients the onset was preceded by an arthropod bite, close to which 3 patients exhibited an erythema chronicum migrans. In the cerebrospinal fluid there was a mononuclear pleocytosis, predominantely by lymphocytes. In the early stages, a plasma cell reaction was frequently encountered. Protein analysis indicated a defect in the blood brain barrier and an intrathecal synthesis of IgG. All patients recovered almost completely from their neurological symptoms within 1-2 months, irrespective of treatment.