We present laboratory data from 22 patients suspected of having neurosyphilis. In two cases the suspicion could not be confirmed, and in 20 cases neurosyphilis was detected. The sera from 17 patients were also assayed for Borrelia-specific antibodies. Suspicious immunoglobulin G antibody indices were detected in nine cases and a suspicious immunoglobulin M antibody index in one. In six of these, stored CSF/serum pairs were available to specify the antibodies by immunoblotting. This allowed for the identification of one patient apparently infected by both Borrelia spp. and Treponema pallidum. In all cases of newly suspected neurosyphilis, we recommend considering neuroborreliosis at the same time.