Invasive pulmonary aspergillosis (IPA) is an increasing cause of morbidity and mortality in patients with hematologic malignancies. A major program of construction work close to our unit prompted us to evaluate the efficacy of itraconazole prophylaxis in preventing IPA in these patients. During September 1994 to December 1995, 77 patients undergoing 96 neutropenic episodes (mean duration, 19.3 days +/- 9.1) received itraconazole as antifungal prophylaxis. All patients were treated in laminar air flow rooms. Itraconazole was administered at a loading dose of 600mg/d, (day 1 to day 3) and 400mg/d on the following days, in 87 instances. In the remaining episodes, the daily dose was 200 or 400mg. Oral doses were adjusted to reach a plasma itraconazole level (PIL) above 1000ng/l. In cases of inadequate PIL or poor oral intake, IV AmphoB was started at a 20 mg daily dose. Five cases of IPA (proven n = 2, probable n = 3) were observed. This represents an incidence of 5.2% of the total number of episodes. One out of 67 (2%) treatment episodes with adequate PIL were associated with IPA as compared to 4 of 29 (14%) episodes with inadequate PIL, (p < 0.02). AmphoB was added in 28 cases because of low PIL (n = 25), and/or antibiotic-resistant fever persistent pulmonary infiltrate (n = 8). These results need to be interpreted with caution, because of the absence of randomization or a control group. The efficacy of Itraconazole in neutropenic patients with high risk IPA has to be confirmed on larger and prospective studies.