Borrelia burgdorferi infection may show disease manifestations in different organ systems, including the skin, heart, central nervous system, peripheral nervous system, and joints. We report two hitherto unknown (to our knowledge) disease manifestations, an arteritis in the central nervous system, and a neuromyopathy of 11 years' duration. Diagnoses were made by demonstrating specific antibodies against B burgdorferi in the cerebrospinal fluid, and elevated specific antibody index. Both patients responded well to treatment, and intrathecal immunologic activity could not be demonstrated after treatment. Serologic analyses (enzyme-linked immunosorbent assay) in serum and cerebrospinal fluid should be performed widely in cases with inflammatory findings in cerebrospinal fluid combined with neurologic disease of unclear origins.