The main clinical and biological features of 22 cases of neurological forms of Lyme disease are reviewed. Radiculitis (n = 15), cranial nevritis (n = 7), meningitis (n = 5) and encephalitis (n = 4) are often associated. Tick bites were previously noticed in only 40% of cases; erythema chronicum migrans in 73%, "one to six months before the onset of neurological symptoms". Titers of Borrelia Burgdorferi antibodies were always above 1/256. Among 18 patients, DR W2 HLA haplotype was present in 15.