Invasive aspergillosis (IA), and particularly invasive pulmonary aspergillosis (IPA), is an important cause of morbidity and mortality in patients who are receiving chemotherapy for acute leukemia (AL), being the the most common invasive mycosis which develops in these patients. Proven invasive aspergillosis has been reported in 6,5% of patients with acute leukemia in a retrospective multicenter study (Pagano, Haematologica 2001) but that frequency may be underestimated, since definite diagnosis is difficult to obtain, particularly in leukemic patients.