This report describes the diagnosis and management of a 16-year-old boy who developed neurological signs and symptoms suggestive of cerebral aspergillosis following a haploidentical bone marrow transplant. A new sandwich enzyme-linked immunosorbent assay (ELISA) for the detection of Aspergillus galactomannan circulating antigens (Platelia Aspergillus, Sanofi Diagnostic Pasteur, France) was used on serum and cerebrospinal fluid to obtain a presumptive diagnosis and to monitor the course of the disease. Having failed conventional therapy with amphotericin B, the patient received compassionate treatment with voriconazole for a period of 37 days. High levels of voriconazole were observed in both serum and cerebrospinal fluid (CSF), with a trend toward accumulation. After 7 days a marked improvement in the patient's neurological symptoms was noted, and ELISA data indicated a corresponding decrease in Aspergillus galactomannan levels in both serum and CSF. Voriconazole was well tolerated, with only transient increases in ALT/AST recorded during therapy. Although the patient survived the acute Aspergillus infection, he subsequently died of an unrelated infection.