We retrospectively studied a consecutive series of 100 patients with acute leukemia and aspergillosis to evaluate the clinical findings and risk factors for colonization of the central nervous system (CNS) by Aspergillus species. The diagnosis of CNS aspergillosis was made in 14 patients on the basis of the following criteria: neurological signs of CNS involvement (13 of 14 patients); cerebral CT scan findings (9 of 12); microbiological findings (6 of 12); and histological findings at autopsy (11 of 11). The majority of patients had severe neurological complications (i.e., hemiparesis or seizures), due mainly to brain abscesses or mycetomas. Autopsies were performed on 11 of 14 patients and provided evidence that CNS localization was secondary to invasive aspergillosis; in each case, the most likely primary focus of infection was the lung. Although all patients had received oral antimycotic prophylaxis and had received timely empirical antifungal treatment, they all died within a median time of 5 days from the onset of neurological symptoms. Analysis of the characteristics of patients with invasive aspergillosis did not reveal any difference between those with CNS localization and those without CNS localization.