To investigate the usefulness of examination of cerebrospinal fluids (CSF) in the diagnosis of central nervous system (CNS) aspergillosis, we examined five patients with either brain abscesses or cerebral infarctions and 11 control patients. CSF samples were subjected to enzyme-linked immunosorbent assay (EIA), latex agglutination test (LA) and polymerase chain reaction (PCR). Cultures of CSF samples were negative in all the patients, but PCR, EIA and LA were positive in five, four and four patients with CNS aspergillosis, respectively. None of these tests were positive in the control patients. CSF examination may be beneficial in the diagnosis of CNS aspergillosis.