A 30-year-old, previously healthy, non-addicted man presented with a chronic spinal meningitis complicated by arachnoiditis and spinal cord compression. Biopsy showed a chronic granulomatous leptomeningitis, in which some cells contained branching septate organisms that were immunostained with an antiserum to Aspergillus fumigatus. Precipitins to A. fumigatus were detected in cerebrospinal fluid (CSF), but not in blood, and aspergillus infection was apparently restricted to the leptomeninges. Clinically successful treatment led to the disappearance of CSF precipitins and oligoclonal bands.