We have used a new, commercial enzyme-linked immunosorbent assay (ELISA, Platelia Aspergillus) to detect Aspergillus antigen in serum, urine and bronchoalveolar lavage (BAL) samples of 105 haematological patients who received empirical amphotericin B treatment for suspected fungal infection. 14% (60/419) of serum and 5% (18/373) of urine samples were positive. Ten-fold concentration of urine increased the number of positive samples to 31 (8%). The antigen was detected in 5 of 20 BAL samples, but fungal culture was negative in all of them. 22 patients had positive antigen test. Serum was positive in 17, urine in 7 and concentrated urine in 12 patients. Six patients had confirmed invasive aspergillosis. In all these patients, antigen was detected in serum, but urine was positive in only 2 patients. Patients whose antigen test turned negative during the amphotericin B treatment had significantly lower mortality than patients with persistently positive antigen test (2/10 vs. 8/8, p = 0.002). We conclude that Aspergillus galactomannan can be detected by ELISA in serum, urine and BAL samples of haematological patients, but the higher sensitivity of serum testing makes it preferable for screening. Disappearance of the antigen during antifungal therapy seems to correlate with good, and persistence with poor, clinical outcome.