Paired serum and cerebrospinal fluid (CSF) samples from 800 patients of a neurological clinic were tested for antibodies to Borrelia burgdorferi. A flagellum enzyme-linked immunosorbent assay was used for antibody screening. All serum/CSF pairs with any elevated antibody response were also tested by a Western blot, a method for confirmation. 65 patients (8.1%) had serum IgG antibodies on ELISA screening and 22 of these (2.8%) were confirmed by Western blot. 20 patients (2.5%) had elevated antibody titers in CSF by ELISA and 12 of these (1.5%) reacted to the Western blot. Clinical features of Bannwarth's syndrome (BS) were present in 12 patients (1.5%) and four patients (0.5%) showed other manifestations of Lyme borreliosis. All patients with Bannwarth's syndrome were positive in serum by both methods and 10 had elevated antibody activity in the CSF proven by the two methods. The combination of a sensitive ELISA for screening and a sensitive and specific Western blot for confirmation reduces the number of positive results but is sensitive in detecting active disease.