 Fungal infections caused by Aspergillus fumigatus are now identified in up to 45 of patients dying from haematological malignancy. There has been a significant increase in deaths from IA over the last 20 years. Our current diagnostic approach is neither sensitive nor specific. The purpose of this study is to prospectively assess the value of current diagnostic tools, as well as test other new diagnostic methods for the diagnosis of IA among haemato-oncology patients undergoing chemotherapy or stem cell transplantation. 